Abstract

This specification defines the bulk of the HTML5 vocabulary, which is further extended by other specifications.

Status of This document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the most recently formally published revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

If you wish to make comments regarding this document, please send them to public-html-comments@w3.org (subscribe, archives) or whatwg@whatwg.org (subscribe, archives), or submit them using our public bug database. All feedback is welcome.

The working groups maintains a list of all bug reports that the editor has not yet tried to address and a list of issues for which the chairs have not yet declared a decision. The editor also maintains a list of all e-mails that he has not yet tried to address. These bugs, issues, and e-mails apply to all HTML specifications, not just this one.

Implementors should be aware that this specification is not stable. Implementors who are not taking part in the discussions are likely to find the specification changing out from under them in incompatible ways. Vendors interested in implementing this specification before it eventually reaches the Candidate Recommendation stage should join the aforementioned mailing lists and take part in the discussions.

The publication of this document by the W3C as a W3C Working Draft does not imply that all of the participants in the W3C HTML working group endorse the contents of the specification. Indeed, for any section of the specification, one can usually find many members of the working group or of the W3C as a whole who object strongly to the current text, the existence of the section at all, or the idea that the working group should even spend time discussing the concept of that section.

The latest stable version of the editor's draft of this specification is always available on the W3C CVS server and in the WHATWG Subversion repository. The latest editor's working copy (which may contain unfinished text in the process of being prepared) contains the latest draft text of this specification (amongst others). For more details, please see the WHATWG FAQ.

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The W3C HTML Working Group is the W3C working group responsible for this specification's progress along the W3C Recommendation track. This specification is the 9 January 2010 Editor's Draft.

This specification is part of a larger specification being produced by the WHATWG. This specification is a module that forms part of the HTML5 series of specifications published at the W3C. It is published separate from other modules of HTML5 in a manner consistent with the principles of maturity, market success, and reusability in other languages described in the Working Group Decision published on January 7th 2010. The HTML5 series of specifications is intended to replace (be a new version of) what was previously the HTML4, XHTML1, and DOM2 HTML specifications.

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

The WHATWG version of this specification is available under a license that permits reuse of the specification text.

Table of Contents

  1. 1 Conformance requirements
  2. 2 Semantics, structure, and APIs of HTML documents
    1. 2.1 Documents
      1. 2.1.1 Documents in the DOM
      2. 2.1.2 Security
      3. 2.1.3 Resource metadata management
      4. 2.1.4 DOM tree accessors
      5. 2.1.5 Creating documents
    2. 2.2 Elements
      1. 2.2.1 Semantics
      2. 2.2.2 Elements in the DOM
      3. 2.2.3 Global attributes
        1. 2.2.3.1 The id attribute
        2. 2.2.3.2 The title attribute
        3. 2.2.3.3 The lang and xml:lang attributes
        4. 2.2.3.4 The xml:base attribute (XML only)
        5. 2.2.3.5 The dir attribute
        6. 2.2.3.6 The class attribute
        7. 2.2.3.7 The style attribute
        8. 2.2.3.8 Embedding custom non-visible data
      4. 2.2.4 Element definitions
      5. 2.2.5 Content models
        1. 2.2.5.1 Kinds of content
          1. 2.2.5.1.1 Metadata content
          2. 2.2.5.1.2 Flow content
          3. 2.2.5.1.3 Sectioning content
          4. 2.2.5.1.4 Heading content
          5. 2.2.5.1.5 Phrasing content
          6. 2.2.5.1.6 Embedded content
          7. 2.2.5.1.7 Interactive content
        2. 2.2.5.2 Transparent content models
        3. 2.2.5.3 Paragraphs
      6. 2.2.6 Annotations for assistive technology products (ARIA)
    3. 2.3 APIs in HTML documents
    4. 2.4 Interactions with XPath and XSLT
    5. 2.5 Dynamic markup insertion
      1. 2.5.1 Opening the input stream
      2. 2.5.2 Closing the input stream
      3. 2.5.3 document.write()
      4. 2.5.4 document.writeln()
      5. 2.5.5 innerHTML
      6. 2.5.6 outerHTML
      7. 2.5.7 insertAdjacentHTML()
  3. 3 The elements of HTML
    1. 3.1 The root element
      1. 3.1.1 The html element
    2. 3.2 Document metadata
      1. 3.2.1 The head element
      2. 3.2.2 The title element
      3. 3.2.3 The base element
      4. 3.2.4 The link element
      5. 3.2.5 The meta element
        1. 3.2.5.1 Standard metadata names
        2. 3.2.5.2 Other metadata names
        3. 3.2.5.3 Pragma directives
        4. 3.2.5.4 Other pragma directives
        5. 3.2.5.5 Specifying the document's character encoding
      6. 3.2.6 The style element
      7. 3.2.7 Styling
    3. 3.3 Scripting
      1. 3.3.1 The script element
        1. 3.3.1.1 Scripting languages
        2. 3.3.1.2 Restrictions for contents of script elements
        3. 3.3.1.3 Inline documentation for external scripts
      2. 3.3.2 The noscript element
    4. 3.4 Sections
      1. 3.4.1 The body element
      2. 3.4.2 The section element
      3. 3.4.3 The nav element
      4. 3.4.4 The article element
      5. 3.4.5 The aside element
      6. 3.4.6 The h1, h2, h3, h4, h5, and h6 elements
      7. 3.4.7 The hgroup element
      8. 3.4.8 The header element
      9. 3.4.9 The footer element
      10. 3.4.10 The address element
      11. 3.4.11 Headings and sections
        1. 3.4.11.1 Creating an outline
    5. 3.5 Grouping content
      1. 3.5.1 The p element
      2. 3.5.2 The hr element
      3. 3.5.3 The br element
      4. 3.5.4 The pre element
      5. 3.5.5 The blockquote element
      6. 3.5.6 The ol element
      7. 3.5.7 The ul element
      8. 3.5.8 The li element
      9. 3.5.9 The dl element
      10. 3.5.10 The dt element
      11. 3.5.11 The dd element
      12. 3.5.12 The div element
    6. 3.6 Text-level semantics
      1. 3.6.1 The a element
      2. 3.6.2 The em element
      3. 3.6.3 The strong element
      4. 3.6.4 The small element
      5. 3.6.5 The cite element
      6. 3.6.6 The q element
      7. 3.6.7 The dfn element
      8. 3.6.8 The abbr element
      9. 3.6.9 The time element
      10. 3.6.10 The code element
      11. 3.6.11 The var element
      12. 3.6.12 The samp element
      13. 3.6.13 The kbd element
      14. 3.6.14 The sub and sup elements
      15. 3.6.15 The i element
      16. 3.6.16 The b element
      17. 3.6.17 The mark element
      18. 3.6.18 The ruby element
      19. 3.6.19 The rt element
      20. 3.6.20 The rp element
      21. 3.6.21 The bdo element
      22. 3.6.22 The span element
      23. 3.6.23 Usage summary
    7. 3.7 Edits
      1. 3.7.1 The ins element
      2. 3.7.2 The del element
      3. 3.7.3 Attributes common to ins and del elements
      4. 3.7.4 Edits and paragraphs
      5. 3.7.5 Edits and lists
    8. 3.8 Embedded content
      1. 3.8.1 The figure element
      2. 3.8.2 The img element
        1. 3.8.2.1 Requirements for providing text to act as an alternative for images
          1. 3.8.2.1.1 A link or button containing nothing but the image
          2. 3.8.2.1.2 A phrase or paragraph with an alternative graphical representation: charts, diagrams, graphs, maps, illustrations
          3. 3.8.2.1.3 A short phrase or label with an alternative graphical representation: icons, logos
          4. 3.8.2.1.4 Text that has been rendered to a graphic for typographical effect
          5. 3.8.2.1.5 A graphical representation of some of the surrounding text
          6. 3.8.2.1.6 A purely decorative image that doesn't add any information
          7. 3.8.2.1.7 A group of images that form a single larger picture with no links
          8. 3.8.2.1.8 A group of images that form a single larger picture with links
          9. 3.8.2.1.9 A key part of the content
          10. 3.8.2.1.10 An image not intended for the user
          11. 3.8.2.1.11 An image in an e-mail or private document intended for a specific person who is known to be able to view images
          12. 3.8.2.1.12 General guidelines
          13. 3.8.2.1.13 Guidance for markup generators
          14. 3.8.2.1.14 Guidance for conformance checkers
      3. 3.8.3 The iframe element
      4. 3.8.4 The embed element
      5. 3.8.5 The object element
      6. 3.8.6 The param element
      7. 3.8.7 The video element
      8. 3.8.8 The audio element
      9. 3.8.9 The source element
      10. 3.8.10 Media elements
        1. 3.8.10.1 Error codes
        2. 3.8.10.2 Location of the media resource
        3. 3.8.10.3 MIME types
        4. 3.8.10.4 Network states
        5. 3.8.10.5 Loading the media resource
        6. 3.8.10.6 Offsets into the media resource
        7. 3.8.10.7 The ready states
        8. 3.8.10.8 Playing the media resource
        9. 3.8.10.9 Seeking
        10. 3.8.10.10 User interface
        11. 3.8.10.11 Time ranges
        12. 3.8.10.12 Event summary
        13. 3.8.10.13 Security and privacy considerations
      11. 3.8.11 The canvas element
        1. 3.8.11.1 Color spaces and color correction
        2. 3.8.11.2 Security with canvas elements
      12. 3.8.12 The map element
      13. 3.8.13 The area element
      14. 3.8.14 Image maps
        1. 3.8.14.1 Authoring
        2. 3.8.14.2 Processing model
      15. 3.8.15 MathML
      16. 3.8.16 SVG
      17. 3.8.17 Dimension attributes
    9. 3.9 Tabular data
      1. 3.9.1 The table element
      2. 3.9.2 The caption element
      3. 3.9.3 The colgroup element
      4. 3.9.4 The col element
      5. 3.9.5 The tbody element
      6. 3.9.6 The thead element
      7. 3.9.7 The tfoot element
      8. 3.9.8 The tr element
      9. 3.9.9 The td element
      10. 3.9.10 The th element
      11. 3.9.11 Attributes common to td and th elements
      12. 3.9.12 Processing model
        1. 3.9.12.1 Forming a table
        2. 3.9.12.2 Forming relationships between data cells and header cells
      13. 3.9.13 Examples
    10. 3.10 Forms
      1. 3.10.1 The form element
      2. 3.10.2 The fieldset element
      3. 3.10.3 The legend element
      4. 3.10.4 The label element
      5. 3.10.5 The input element
        1. 3.10.5.1 States of the type attribute
          1. 3.10.5.1.1 Hidden state
          2. 3.10.5.1.2 Text state and Search state
          3. 3.10.5.1.3 Telephone state
          4. 3.10.5.1.4 URL state
          5. 3.10.5.1.5 E-mail state
          6. 3.10.5.1.6 Password state
          7. 3.10.5.1.7 Date and Time state
          8. 3.10.5.1.8 Date state
          9. 3.10.5.1.9 Month state
          10. 3.10.5.1.10 Week state
          11. 3.10.5.1.11 Time state
          12. 3.10.5.1.12 Local Date and Time state
          13. 3.10.5.1.13 Number state
          14. 3.10.5.1.14 Range state
          15. 3.10.5.1.15 Color state
          16. 3.10.5.1.16 Checkbox state
          17. 3.10.5.1.17 Radio Button state
          18. 3.10.5.1.18 File Upload state
          19. 3.10.5.1.19 Submit Button state
          20. 3.10.5.1.20 Image Button state
          21. 3.10.5.1.21 Reset Button state
          22. 3.10.5.1.22 Button state
        2. 3.10.5.2 Common input element attributes
          1. 3.10.5.2.1 The autocomplete attribute
          2. 3.10.5.2.2 The list attribute
          3. 3.10.5.2.3 The readonly attribute
          4. 3.10.5.2.4 The size attribute
          5. 3.10.5.2.5 The required attribute
          6. 3.10.5.2.6 The multiple attribute
          7. 3.10.5.2.7 The maxlength attribute
          8. 3.10.5.2.8 The pattern attribute
          9. 3.10.5.2.9 The min and max attributes
          10. 3.10.5.2.10 The step attribute
          11. 3.10.5.2.11 The placeholder attribute
        3. 3.10.5.3 Common input element APIs
        4. 3.10.5.4 Common event behaviors
      6. 3.10.6 The button element
      7. 3.10.7 The select element
      8. 3.10.8 The datalist element
      9. 3.10.9 The optgroup element
      10. 3.10.10 The option element
      11. 3.10.11 The textarea element
      12. 3.10.12 The keygen element
      13. 3.10.13 The output element
      14. 3.10.14 The progress element
      15. 3.10.15 The meter element
      16. 3.10.16 Association of controls and forms
      17. 3.10.17 Attributes common to form controls
        1. 3.10.17.1 Naming form controls
        2. 3.10.17.2 Enabling and disabling form controls
        3. 3.10.17.3 A form control's value
        4. 3.10.17.4 Autofocusing a form control
        5. 3.10.17.5 Limiting user input length
        6. 3.10.17.6 Form submission
      18. 3.10.18 Constraints
        1. 3.10.18.1 Definitions
        2. 3.10.18.2 Constraint validation
        3. 3.10.18.3 The constraint validation API
        4. 3.10.18.4 Security
      19. 3.10.19 Form submission
        1. 3.10.19.1 Introduction
        2. 3.10.19.2 Implicit submission
        3. 3.10.19.3 Form submission algorithm
        4. 3.10.19.4 URL-encoded form data
        5. 3.10.19.5 Multipart form data
        6. 3.10.19.6 Plain text form data
      20. 3.10.20 Resetting a form
      21. 3.10.21 Event dispatch
    11. 3.11 Interactive elements
      1. 3.11.1 The details element
      2. 3.11.2 The command element
      3. 3.11.3 The menu element
        1. 3.11.3.1 Introduction
        2. 3.11.3.2 Building menus and toolbars
        3. 3.11.3.3 Context menus
        4. 3.11.3.4 Toolbars
      4. 3.11.4 Commands
        1. 3.11.4.1 Using the a element to define a command
        2. 3.11.4.2 Using the button element to define a command
        3. 3.11.4.3 Using the input element to define a command
        4. 3.11.4.4 Using the option element to define a command
        5. 3.11.4.5 Using the command element to define a command
        6. 3.11.4.6 Using the accesskey attribute on a label element to define a command
        7. 3.11.4.7 Using the accesskey attribute on a legend element to define a command
        8. 3.11.4.8 Using the accesskey attribute to define a command on other elements
    12. 3.12 Common idioms without dedicated elements
      1. 3.12.1 Tag clouds
      2. 3.12.2 Conversations
      3. 3.12.3 Footnotes
    13. 3.13 Matching HTML elements using selectors
    14. 3.14 Converting HTML to other formats
      1. 3.14.1 Atom
  4. 4 The HTML syntax
    1. 4.1 Writing HTML documents
      1. 4.1.1 The DOCTYPE
      2. 4.1.2 Elements
        1. 4.1.2.1 Start tags
        2. 4.1.2.2 End tags
        3. 4.1.2.3 Attributes
        4. 4.1.2.4 Optional tags
        5. 4.1.2.5 Restrictions on content models
        6. 4.1.2.6 Restrictions on the contents of raw text and RCDATA elements
      3. 4.1.3 Text
        1. 4.1.3.1 Newlines
      4. 4.1.4 Character references
      5. 4.1.5 CDATA sections
      6. 4.1.6 Comments
    2. 4.2 Parsing HTML documents
      1. 4.2.1 Overview of the parsing model
      2. 4.2.2 The input stream
        1. 4.2.2.1 Determining the character encoding
        2. 4.2.2.2 Character encodings
        3. 4.2.2.3 Preprocessing the input stream
        4. 4.2.2.4 Changing the encoding while parsing
      3. 4.2.3 Parse state
        1. 4.2.3.1 The insertion mode
        2. 4.2.3.2 The stack of open elements
        3. 4.2.3.3 The list of active formatting elements
        4. 4.2.3.4 The element pointers
        5. 4.2.3.5 Other parsing state flags
      4. 4.2.4 Tokenization
        1. 4.2.4.1 Data state
        2. 4.2.4.2 Character reference in data state
        3. 4.2.4.3 RCDATA state
        4. 4.2.4.4 Character reference in RCDATA state
        5. 4.2.4.5 RAWTEXT state
        6. 4.2.4.6 Script data state
        7. 4.2.4.7 PLAINTEXT state
        8. 4.2.4.8 Tag open state
        9. 4.2.4.9 Close tag open state
        10. 4.2.4.10 Tag name state
        11. 4.2.4.11 RCDATA less-than sign state
        12. 4.2.4.12 RCDATA end tag open state
        13. 4.2.4.13 RCDATA end tag name state
        14. 4.2.4.14 RAWTEXT less-than sign state
        15. 4.2.4.15 RAWTEXT end tag open state
        16. 4.2.4.16 RAWTEXT end tag name state
        17. 4.2.4.17 Script data less-than sign state
        18. 4.2.4.18 Script data end tag open state
        19. 4.2.4.19 Script data end tag name state
        20. 4.2.4.20 Script data escape start state
        21. 4.2.4.21 Script data escape start dash state
        22. 4.2.4.22 Script data escaped state
        23. 4.2.4.23 Script data escaped dash state
        24. 4.2.4.24 Script data escaped dash dash state
        25. 4.2.4.25 Script data escaped less-than sign state
        26. 4.2.4.26 Script data escaped end tag open state
        27. 4.2.4.27 Script data escaped end tag name state
        28. 4.2.4.28 Script data double escape start state
        29. 4.2.4.29 Script data double escaped state
        30. 4.2.4.30 Script data double escaped dash state
        31. 4.2.4.31 Script data double escaped dash dash state
        32. 4.2.4.32 Script data double escaped less-than sign state
        33. 4.2.4.33 Script data double escape end state
        34. 4.2.4.34 Before attribute name state
        35. 4.2.4.35 Attribute name state
        36. 4.2.4.36 After attribute name state
        37. 4.2.4.37 Before attribute value state
        38. 4.2.4.38 Attribute value (double-quoted) state
        39. 4.2.4.39 Attribute value (single-quoted) state
        40. 4.2.4.40 Attribute value (unquoted) state
        41. 4.2.4.41 Character reference in attribute value state
        42. 4.2.4.42 After attribute value (quoted) state
        43. 4.2.4.43 Self-closing start tag state
        44. 4.2.4.44 Bogus comment state
        45. 4.2.4.45 Markup declaration open state
        46. 4.2.4.46 Comment start state
        47. 4.2.4.47 Comment start dash state
        48. 4.2.4.48 Comment state
        49. 4.2.4.49 Comment end dash state
        50. 4.2.4.50 Comment end state
        51. 4.2.4.51 Comment end bang state
        52. 4.2.4.52 Comment end space state
        53. 4.2.4.53 DOCTYPE state
        54. 4.2.4.54 Before DOCTYPE name state
        55. 4.2.4.55 DOCTYPE name state
        56. 4.2.4.56 After DOCTYPE name state
        57. 4.2.4.57 After DOCTYPE public keyword state
        58. 4.2.4.58 Before DOCTYPE public identifier state
        59. 4.2.4.59 DOCTYPE public identifier (double-quoted) state
        60. 4.2.4.60 DOCTYPE public identifier (single-quoted) state
        61. 4.2.4.61 After DOCTYPE public identifier state
        62. 4.2.4.62 Between DOCTYPE public and system identifiers state
        63. 4.2.4.63 After DOCTYPE system keyword state
        64. 4.2.4.64 Before DOCTYPE system identifier state
        65. 4.2.4.65 DOCTYPE system identifier (double-quoted) state
        66. 4.2.4.66 DOCTYPE system identifier (single-quoted) state
        67. 4.2.4.67 After DOCTYPE system identifier state
        68. 4.2.4.68 Bogus DOCTYPE state
        69. 4.2.4.69 CDATA section state
        70. 4.2.4.70 Tokenizing character references
      5. 4.2.5 Tree construction
        1. 4.2.5.1 Creating and inserting elements
        2. 4.2.5.2 Closing elements that have implied end tags
        3. 4.2.5.3 Foster parenting
        4. 4.2.5.4 The "initial" insertion mode
        5. 4.2.5.5 The "before html" insertion mode
        6. 4.2.5.6 The "before head" insertion mode
        7. 4.2.5.7 The "in head" insertion mode
        8. 4.2.5.8 The "in head noscript" insertion mode
        9. 4.2.5.9 The "after head" insertion mode
        10. 4.2.5.10 The "in body" insertion mode
        11. 4.2.5.11 The "text" insertion mode
        12. 4.2.5.12 The "in table" insertion mode
        13. 4.2.5.13 The "in table text" insertion mode
        14. 4.2.5.14 The "in caption" insertion mode
        15. 4.2.5.15 The "in column group" insertion mode
        16. 4.2.5.16 The "in table body" insertion mode
        17. 4.2.5.17 The "in row" insertion mode
        18. 4.2.5.18 The "in cell" insertion mode
        19. 4.2.5.19 The "in select" insertion mode
        20. 4.2.5.20 The "in select in table" insertion mode
        21. 4.2.5.21 The "in foreign content" insertion mode
        22. 4.2.5.22 The "after body" insertion mode
        23. 4.2.5.23 The "in frameset" insertion mode
        24. 4.2.5.24 The "after frameset" insertion mode
        25. 4.2.5.25 The "after after body" insertion mode
        26. 4.2.5.26 The "after after frameset" insertion mode
      6. 4.2.6 The end
      7. 4.2.7 Coercing an HTML DOM into an infoset
      8. 4.2.8 An introduction to error handling and strange cases in the parser
        1. 4.2.8.1 Misnested tags: <b><i></b></i>
        2. 4.2.8.2 Misnested tags: <b><p></b></p>
        3. 4.2.8.3 Unexpected markup in tables
        4. 4.2.8.4 Scripts that modify the page as it is being parsed
    3. 4.3 Namespaces
    4. 4.4 Serializing HTML fragments
    5. 4.5 Parsing HTML fragments
    6. 4.6 Named character references
  5. 5 The XHTML syntax
    1. 5.1 Writing XHTML documents
    2. 5.2 Parsing XHTML documents
    3. 5.3 Serializing XHTML fragments
    4. 5.4 Parsing XHTML fragments
  6. 6 Rendering
    1. 6.1 Introduction
    2. 6.2 The CSS user agent style sheet and presentational hints
      1. 6.2.1 Introduction
      2. 6.2.2 Display types
      3. 6.2.3 Margins and padding
      4. 6.2.4 Alignment
      5. 6.2.5 Fonts and colors
      6. 6.2.6 Punctuation and decorations
      7. 6.2.7 Resetting rules for inherited properties
      8. 6.2.8 The hr element
      9. 6.2.9 The fieldset element
    3. 6.3 Replaced elements
      1. 6.3.1 Embedded content
      2. 6.3.2 Images
      3. 6.3.3 Attributes for embedded content and images
      4. 6.3.4 Image maps
      5. 6.3.5 Toolbars
    4. 6.4 Bindings
      1. 6.4.1 Introduction
      2. 6.4.2 The button element
      3. 6.4.3 The details element
      4. 6.4.4 The input element as a text entry widget
      5. 6.4.5 The input element as domain-specific widgets
      6. 6.4.6 The input element as a range control
      7. 6.4.7 The input element as a color well
      8. 6.4.8 The input element as a check box and radio button widgets
      9. 6.4.9 The input element as a file upload control
      10. 6.4.10 The input element as a button
      11. 6.4.11 The marquee element
      12. 6.4.12 The meter element
      13. 6.4.13 The progress element
      14. 6.4.14 The select element
      15. 6.4.15 The textarea element
      16. 6.4.16 The keygen element
      17. 6.4.17 The time element
    5. 6.5 Frames and framesets
    6. 6.6 Interactive media
      1. 6.6.1 Links, forms, and navigation
      2. 6.6.2 The title attribute
      3. 6.6.3 Editing hosts
    7. 6.7 Print media
    8. 6.8 Interaction with CSS
      1. 6.8.1 Selectors
  7. 7 Obsolete features
    1. 7.1 Obsolete but conforming features
      1. 7.1.1 Warnings for obsolete but conforming features
    2. 7.2 Non-conforming features
    3. 7.3 Requirements for implementations
      1. 7.3.1 The applet element
      2. 7.3.2 The marquee element
      3. 7.3.3 Frames
      4. 7.3.4 Other elements, attributes and APIs
  8. 8 IANA considerations
    1. 8.1 text/html
    2. 8.2 application/xhtml+xml
    3. 8.3 text/cache-manifest
    4. 8.4 text/ping
    5. 8.5 Ping-From
    6. 8.6 Ping-To
  9. Index
    1. Elements
    2. Attributes
    3. Interfaces
    4. Events
  10. References
  11. Acknowledgements

1 Conformance requirements

Status: Last call for comments

This specification is an HTML specification. All the conformance requirements, conformance classes, definitions, dependencies, terminology, and typographical conventions described in the HTML5 Core specification apply to this specification. [HTML5CORE]

For an introduction to the HTML5 series of specifications, please see the HTML5 Introduction specification. [HTML5INTRO]

2 Semantics, structure, and APIs of HTML documents

Status: Last call for comments

2.1 Documents

Status: Last call for comments

Every XML and HTML document in an HTML UA is represented by a Document object. [DOMCORE]

The document's address is an absolute URL that is set when the Document is created. The document's current address is an absolute URL that can change during the lifetime of the Document, for example when the user navigates to a fragment identifier on the page. The document's current address must be set to the document's address when the Document is created.

Interactive user agents typically expose the document's current address in their user interface.

When a Document is created by a script using the createDocument() or createHTMLDocument() APIs, the document's address is the same as the document's address of the active document of the script's browsing context.

Document objects are assumed to be XML documents unless they are flagged as being HTML documents when they are created. Whether a document is an HTML document or an XML document affects the behavior of certain APIs and the case-sensitivity of some selectors.

2.1.1 Documents in the DOM

Status: Last call for comments

All Document objects (in user agents implementing this specification) must also implement the HTMLDocument interface, available using binding-specific methods. (This is the case whether or not the document in question is an HTML document or indeed whether it contains any HTML elements at all.) Document objects must also implement the document-level interface of any other namespaces that the UA supports.

For example, if an HTML implementation also supports SVG, then the Document object implements both HTMLDocument and SVGDocument.

Because the HTMLDocument interface is now obtained using binding-specific casting methods instead of simply being the primary interface of the document object, it is no longer defined as inheriting from Document.

[OverrideBuiltins]
interface HTMLDocument {
  // resource metadata management
  [PutForwards=href] readonly attribute Location location;
  readonly attribute DOMString URL;
           attribute DOMString domain;
  readonly attribute DOMString referrer;
           attribute DOMString cookie;
  readonly attribute DOMString lastModified;
  readonly attribute DOMString compatMode;
           attribute DOMString charset;
  readonly attribute DOMString characterSet;
  readonly attribute DOMString defaultCharset;
  readonly attribute DOMString readyState;

  // DOM tree accessors
  getter any (in DOMString name);
           attribute DOMString title;
           attribute DOMString dir;
           attribute HTMLElement body;
  readonly attribute HTMLHeadElement head;
  readonly attribute HTMLCollection images;
  readonly attribute HTMLCollection embeds;
  readonly attribute HTMLCollection plugins;
  readonly attribute HTMLCollection links;
  readonly attribute HTMLCollection forms;
  readonly attribute HTMLCollection scripts;
  NodeList getElementsByName(in DOMString elementName);
  NodeList getElementsByClassName(in DOMString classNames);

  // dynamic markup insertion
           attribute DOMString innerHTML;
  HTMLDocument open(in optional DOMString type, in optional DOMString replace);
  WindowProxy open(in DOMString url, in DOMString name, in DOMString features, in optional boolean replace);
  void close();
  void write(in DOMString... text);
  void writeln(in DOMString... text);

  // user interaction
  Selection getSelection();
  readonly attribute Element activeElement;
  boolean hasFocus();
           attribute DOMString designMode;
  boolean execCommand(in DOMString commandId);
  boolean execCommand(in DOMString commandId, in boolean showUI);
  boolean execCommand(in DOMString commandId, in boolean showUI, in DOMString value);
  boolean queryCommandEnabled(in DOMString commandId);
  boolean queryCommandIndeterm(in DOMString commandId);
  boolean queryCommandState(in DOMString commandId);
  boolean queryCommandSupported(in DOMString commandId);
  DOMString queryCommandValue(in DOMString commandId);
  readonly attribute HTMLCollection commands;

  // event handler IDL attributes
           attribute Function onabort;
           attribute Function onblur;
           attribute Function oncanplay;
           attribute Function oncanplaythrough;
           attribute Function onchange;
           attribute Function onclick;
           attribute Function oncontextmenu;
           attribute Function ondblclick;
           attribute Function ondrag;
           attribute Function ondragend;
           attribute Function ondragenter;
           attribute Function ondragleave;
           attribute Function ondragover;
           attribute Function ondragstart;
           attribute Function ondrop;
           attribute Function ondurationchange;
           attribute Function onemptied;
           attribute Function onended;
           attribute Function onerror;
           attribute Function onfocus;
           attribute Function onformchange;
           attribute Function onforminput;
           attribute Function oninput;
           attribute Function oninvalid;
           attribute Function onkeydown;
           attribute Function onkeypress;
           attribute Function onkeyup;
           attribute Function onload;
           attribute Function onloadeddata;
           attribute Function onloadedmetadata;
           attribute Function onloadstart;
           attribute Function onmousedown;
           attribute Function onmousemove;
           attribute Function onmouseout;
           attribute Function onmouseover;
           attribute Function onmouseup;
           attribute Function onmousewheel;
           attribute Function onpause;
           attribute Function onplay;
           attribute Function onplaying;
           attribute Function onprogress;
           attribute Function onratechange;
           attribute Function onreadystatechange;
           attribute Function onscroll;
           attribute Function onseeked;
           attribute Function onseeking;
           attribute Function onselect;
           attribute Function onshow;
           attribute Function onstalled;
           attribute Function onsubmit;
           attribute Function onsuspend;
           attribute Function ontimeupdate;
           attribute Function onvolumechange;
           attribute Function onwaiting;
};
Document implements HTMLDocument;

Since the HTMLDocument interface holds methods and attributes related to a number of disparate features, the members of this interface are described in various different sections.

2.1.2 Security

Status: Last call for comments

User agents must raise a SECURITY_ERR exception whenever any of the members of an HTMLDocument object are accessed by scripts whose effective script origin is not the same as the Document's effective script origin.

2.1.3 Resource metadata management

Status: Last call for comments

document . URL

Returns the document's address.

document . referrer

Returns the address of the Document from which the user navigated to this one, unless it was blocked or there was no such document, in which case it returns the empty string.

The noreferrer link type can be used to block the referrer.

The URL attribute must return the document's address.

The referrer attribute must return either the current address of the active document of the source browsing context at the time the navigation was started (that is, the page which navigated the browsing context to the current document), with any <fragment> component removed; or the empty string if there is no such originating page, or if the UA has been configured not to report referrers in this case, or if the navigation was initiated for a hyperlink with a noreferrer keyword.

In the case of HTTP, the referrer IDL attribute will match the Referer (sic) header that was sent when fetching the current page.

Typically user agents are configured to not report referrers in the case where the referrer uses an encrypted protocol and the current page does not (e.g. when navigating from an https: page to an http: page).


document . cookie [ = value ]

Returns the HTTP cookies that apply to the Document. If there are no cookies or cookies can't be applied to this resource, the empty string will be returned.

Can be set, to add a new cookie to the element's set of HTTP cookies.

If the Document has no browsing context an INVALID_STATE_ERR exception will be thrown. If the contents are sandboxed into a unique origin, a SECURITY_ERR exception will be thrown.

The cookie attribute represents the cookies of the resource.

On getting, if the document is not associated with a browsing context then the user agent must raise an INVALID_STATE_ERR exception. Otherwise, if the sandboxed origin browsing context flag was set on the browsing context of the Document when the Document was created, the user agent must raise a SECURITY_ERR exception. Otherwise, if the document's address does not use a server-based naming authority, it must return the empty string. Otherwise, it must first obtain the storage mutex and then return the cookie-string for the document's address for a "non-HTTP" API. [COOKIES]

On setting, if the document is not associated with a browsing context then the user agent must raise an INVALID_STATE_ERR exception. Otherwise, if the sandboxed origin browsing context flag was set on the browsing context of the Document when the Document was created, the user agent must raise a SECURITY_ERR exception. Otherwise, if the document's address does not use a server-based naming authority, it must do nothing. Otherwise, the user agent must obtain the storage mutex and then act as it would when receiving a set-cookie-string for the document's address via a "non-HTTP" API, consisting of the new value. [COOKIES]

Since the cookie attribute is accessible across frames, the path restrictions on cookies are only a tool to help manage which cookies are sent to which parts of the site, and are not in any way a security feature.


document . lastModified

Returns the date of the last modification to the document, as reported by the server, in the form "MM/DD/YYYY hh:mm:ss".

If the last modification date is not known, the current time is returned instead.

The lastModified attribute, on getting, must return the date and time of the Document's source file's last modification, in the user's local time zone, in the following format:

  1. The month component of the date.
  2. A U+002F SOLIDUS character (/).
  3. The day component of the date.
  4. A U+002F SOLIDUS character (/).
  5. The year component of the date.
  6. A U+0020 SPACE character.
  7. The hours component of the time.
  8. A U+003A COLON character (:).
  9. The minutes component of the time.
  10. A U+003A COLON character (:).
  11. The seconds component of the time.

All the numeric components above, other than the year, must be given as two digits in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9) representing the number in base ten, zero-padded if necessary. The year must be given as the shortest possible string of four or more digits in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9) representing the number in base ten, zero-padded if necessary.

The Document's source file's last modification date and time must be derived from relevant features of the networking protocols used, e.g. from the value of the HTTP Last-Modified header of the document, or from metadata in the file system for local files. If the last modification date and time are not known, the attribute must return the current date and time in the above format.


document . compatMode

In a conforming document, returns the string "CSS1Compat". (In quirks mode documents, returns the string "BackCompat", but a conforming document can never trigger quirks mode.)

A Document is always set to one of three modes: no quirks mode, the default; quirks mode, used typically for legacy documents; and limited quirks mode, also known as "almost standards" mode. The mode is only ever changed from the default by the HTML parser, based on the presence, absence, or value of the DOCTYPE string.

The compatMode IDL attribute must return the literal string "CSS1Compat" unless the document has been set to quirks mode by the HTML parser, in which case it must instead return the literal string "BackCompat".


document . charset [ = value ]

Returns the document's character encoding.

Can be set, to dynamically change the document's character encoding.

New values that are not IANA-registered aliases supported by the user agent are ignored.

document . characterSet

Returns the document's character encoding.

document . defaultCharset

Returns what might be the user agent's default character encoding.

Documents have an associated character encoding. When a Document object is created, the document's character encoding must be initialized to UTF-16. Various algorithms during page loading affect this value, as does the charset setter. [IANACHARSET]

The charset IDL attribute must, on getting, return the preferred MIME name of the document's character encoding. On setting, if the new value is an IANA-registered alias for a character encoding supported by the user agent, the document's character encoding must be set to that character encoding. (Otherwise, nothing happens.)

The characterSet IDL attribute must, on getting, return the preferred MIME name of the document's character encoding.

The defaultCharset IDL attribute must, on getting, return the preferred MIME name of a character encoding, possibly the user's default encoding, or an encoding associated with the user's current geographical location, or any arbitrary encoding name.


document . readyState

Returns "loading" while the Document is loading, and "complete" once it has loaded.

The readystatechange event fires on the Document object when this value changes.

Each document has a current document readiness. When a Document object is created, it must have its current document readiness set to the string "loading" if the document is associated with an HTML parser or an XML parser, or to the string "complete" otherwise. Various algorithms during page loading affect this value. When the value is set, the user agent must fire a simple event named readystatechange at the Document object.

A Document is said to have an active parser if it is associated with an HTML parser or an XML parser that has not yet been stopped or aborted.

The readyState IDL attribute must, on getting, return the current document readiness.

2.1.4 DOM tree accessors

Status: Last call for comments

The html element of a document is the document's root element, if there is one and it's an html element, or null otherwise.


document . head

Returns the head element.

The head element of a document is the first head element that is a child of the html element, if there is one, or null otherwise.

The head attribute, on getting, must return the head element of the document (a head element or null).


document . title [ = value ]

Returns the document's title, as given by the title element.

Can be set, to update the document's title. If there is no head element, the new value is ignored.

In SVG documents, the SVGDocument interface's title attribute takes precedence.

The title element of a document is the first title element in the document (in tree order), if there is one, or null otherwise.

The title attribute must, on getting, run the following algorithm:

  1. If the root element is an svg element in the "http://www.w3.org/2000/svg" namespace, and the user agent supports SVG, then return the value that would have been returned by the IDL attribute of the same name on the SVGDocument interface. [SVG]

  2. Otherwise, let value be a concatenation of the data of all the child text nodes of the title element, in tree order, or the empty string if the title element is null.

  3. Replace any sequence of one or more consecutive space characters in value with a single U+0020 SPACE character.

  4. Remove any leading or trailing space characters in value.

  5. Return value.

On setting, the following algorithm must be run. Mutation events must be fired as appropriate.

  1. If the root element is an svg element in the "http://www.w3.org/2000/svg" namespace, and the user agent supports SVG, then the setter must defer to the setter for the IDL attribute of the same name on the SVGDocument interface (if it is readonly, then this will raise an exception). Stop the algorithm here. [SVG]

  2. If the title element is null and the head element is null, then the attribute must do nothing. Stop the algorithm here.
  3. If the title element is null, then a new title element must be created and appended to the head element. Let element be that element. Otherwise, let element be the title element.
  4. The children of element (if any) must all be removed.
  5. A single Text node whose data is the new value being assigned must be appended to element.

The title attribute on the HTMLDocument interface should shadow the attribute of the same name on the SVGDocument interface when the user agent supports both HTML and SVG. [SVG]


document . body [ = value ]

Returns the body element.

Can be set, to replace the body element.

If the new value is not a body or frameset element, this will throw a HIERARCHY_REQUEST_ERR exception.

The body element of a document is the first child of the html element that is either a body element or a frameset element. If there is no such element, it is null. If the body element is null, then when the specification requires that events be fired at "the body element", they must instead be fired at the Document object.

The body attribute, on getting, must return the body element of the document (either a body element, a frameset element, or null). On setting, the following algorithm must be run:

  1. If the new value is not a body or frameset element, then raise a HIERARCHY_REQUEST_ERR exception and abort these steps.
  2. Otherwise, if the new value is the same as the body element, do nothing. Abort these steps.
  3. Otherwise, if the body element is not null, then replace that element with the new value in the DOM, as if the root element's replaceChild() method had been called with the new value and the incumbent body element as its two arguments respectively, then abort these steps.
  4. Otherwise, the body element is null. Append the new value to the root element.

document . images

Returns an HTMLCollection of the img elements in the Document.

document . embeds
document . plugins

Return an HTMLCollection of the embed elements in the Document.

document . links

Returns an HTMLCollection of the a and area elements in the Document that have href attributes.

document . forms

Return an HTMLCollection of the form elements in the Document.

document . scripts

Return an HTMLCollection of the script elements in the Document.

The images attribute must return an HTMLCollection rooted at the Document node, whose filter matches only img elements.

The embeds attribute must return an HTMLCollection rooted at the Document node, whose filter matches only embed elements.

The plugins attribute must return the same object as that returned by the embeds attribute.

The links attribute must return an HTMLCollection rooted at the Document node, whose filter matches only a elements with href attributes and area elements with href attributes.

The forms attribute must return an HTMLCollection rooted at the Document node, whose filter matches only form elements.

The scripts attribute must return an HTMLCollection rooted at the Document node, whose filter matches only script elements.


collection = document . getElementsByName(name)

Returns a NodeList of elements in the Document that have a name attribute with the value name.

collection = document . getElementsByClassName(classes)
collection = element . getElementsByClassName(classes)

Returns a NodeList of the elements in the object on which the method was invoked (a Document or an Element) that have all the classes given by classes.

The classes argument is interpreted as a space-separated list of classes.

The getElementsByName(name) method takes a string name, and must return a live NodeList containing all the HTML elements in that document that have a name attribute whose value is equal to the name argument (in a case-sensitive manner), in tree order.

The getElementsByClassName(classNames) method takes a string that contains a set of space-separated tokens representing classes. When called, the method must return a live NodeList object containing all the elements in the document, in tree order, that have all the classes specified in that argument, having obtained the classes by splitting a string on spaces. (Duplicates are ignored.) If there are no tokens specified in the argument, then the method must return an empty NodeList. If the document is in quirks mode, then the comparisons for the classes must be done in an ASCII case-insensitive manner, otherwise, the comparisons must be done in a case-sensitive manner.

The getElementsByClassName(classNames) method on the HTMLElement interface must return a live NodeList with the nodes that the HTMLDocument getElementsByClassName() method would return when passed the same argument(s), excluding any elements that are not descendants of the HTMLElement object on which the method was invoked.

HTML, SVG, and MathML elements define which classes they are in by having an attribute with no namespace with the name class containing a space-separated list of classes to which the element belongs. Other specifications may also allow elements in their namespaces to be labeled as being in specific classes.

Given the following XHTML fragment:

<div id="example">
 <p id="p1" class="aaa bbb"/>
 <p id="p2" class="aaa ccc"/>
 <p id="p3" class="bbb ccc"/>
</div>

A call to document.getElementById('example').getElementsByClassName('aaa') would return a NodeList with the two paragraphs p1 and p2 in it.

A call to getElementsByClassName('ccc bbb') would only return one node, however, namely p3. A call to document.getElementById('example').getElementsByClassName('bbb  ccc ') would return the same thing.

A call to getElementsByClassName('aaa,bbb') would return no nodes; none of the elements above are in the "aaa,bbb" class.


The HTMLDocument interface supports named properties. The names of the supported named properties at any moment consist of the values of the name content attributes of all the applet, embed, form, iframe, img, and fallback-free object elements in the Document that have name content attributes, and the values of the id content attributes of all the applet and fallback-free object elements in the Document that have id content attributes, and the values of the id content attributes of all the img elements in the Document that have both name content attributes and id content attributes.

When the HTMLDocument object is indexed for property retrieval using a name name, then the user agent must return the value obtained using the following steps:

  1. Let elements be the list of named elements with the name name in the Document.

    There will be at least one such element, by definition.

  2. If elements has only one element, and that element is an iframe element, then return the WindowProxy object of the nested browsing context represented by that iframe element, and abort these steps.

  3. Otherwise, if elements has only one element, return that element and abort these steps.

  4. Otherwise return an HTMLCollection rooted at the Document node, whose filter matches only named elements with the name name.

Named elements with the name name, for the purposes of the above algorithm, are those that are either:

An object element is said to be fallback-free if it has no object or embed descendants.


The dir attribute on the HTMLDocument interface is defined along with the dir content attribute.

2.1.5 Creating documents

Status: Last call for comments

XML documents can be created from script using the createDocument() method on the DOMImplementation interface.

HTML documents can be created using the createHTMLDocument() method:

[Supplemental, NoInterfaceObject]
interface DOMHTMLImplementation {
  Document createHTMLDocument(in DOMString title);
};
DOMImplementation implements DOMHTMLImplementation;

The createHTMLDocument(title) method, when invoked, must run the following steps:

  1. Let doc be a newly created Document object.

  2. Mark doc as being an HTML document.

  3. Create a DocumentType node with the name attribute set to the string "html", and the other attributes specific to DocumentType objects set to the empty string, null, and empty lists, as appropriate. Append the newly created node to doc.

  4. Create an html element, and append it to doc.

  5. Create a head element, and append it to the html element created in the previous step.

  6. Create a title element, and append it to the head element created in the previous step.

  7. Create a Text node, and set its data attribute to the string given by the method's argument (which could be the empty string). Append it to the title element created in the previous step.

  8. Create a body element, and append it to the html element created in the earlier step.

  9. Return doc.

2.2 Elements

Status: Last call for comments

2.2.1 Semantics

Status: Last call for comments. ISSUE-41 (Decentralized-extensibility) blocks progress to Last Call

Elements, attributes, and attribute values in HTML are defined (by this specification) to have certain meanings (semantics). For example, the ol element represents an ordered list, and the lang attribute represents the language of the content.

Authors must not use elements, attributes, or attribute values for purposes other than their appropriate intended semantic purpose. Authors must not use elements, attributes, or attribute values that are not permitted by this specification or other applicable specifications.

For example, the following document is non-conforming, despite being syntactically correct:

<!DOCTYPE HTML>
<html lang="en-GB">
 <head> <title> Demonstration </title> </head>
 <body>
  <table>
   <tr> <td> My favourite animal is the cat. </td> </tr>
   <tr>
    <td>
     —<a href="http://example.org/~ernest/"><cite>Ernest</cite></a>,
     in an essay from 1992
    </td>
   </tr>
  </table>
 </body>
</html>

...because the data placed in the cells is clearly not tabular data (and the cite element mis-used). A corrected version of this document might be:

<!DOCTYPE HTML>
<html lang="en-GB">
 <head> <title> Demonstration </title> </head>
 <body>
  <blockquote>
   <p> My favourite animal is the cat. </p>
  </blockquote>
  <p>
   —<a href="http://example.org/~ernest/">Ernest</a>,
   in an essay from 1992
  </p>
 </body>
</html>

This next document fragment, intended to represent the heading of a corporate site, is similarly non-conforming because the second line is not intended to be a heading of a subsection, but merely a subheading or subtitle (a subordinate heading for the same section).

<body>
 <h1>ABC Company</h1>
 <h2>Leading the way in widget design since 1432</h2>
 ...

The hgroup element is intended for these kinds of situations:

<body>
 <hgroup>
  <h1>ABC Company</h1>
  <h2>Leading the way in widget design since 1432</h2>
 </hgroup>
 ...

In the next example, there is a non-conforming attribute value ("carpet") and a non-conforming attribute ("texture"), which is not permitted by this specification:

<label>Carpet: <input type="carpet" name="c" texture="deep pile"></label>

Here would be an alternative and correct way to mark this up:

<label>Carpet: <input type="text" class="carpet" name="c" data-texture="deep pile"></label>

Through scripting and using other mechanisms, the values of attributes, text, and indeed the entire structure of the document may change dynamically while a user agent is processing it. The semantics of a document at an instant in time are those represented by the state of the document at that instant in time, and the semantics of a document can therefore change over time. User agents must update their presentation of the document as this occurs.

HTML has a progress element that describes a progress bar. If its "value" attribute is dynamically updated by a script, the UA would update the rendering to show the progress changing.

2.2.2 Elements in the DOM

Status: Last call for comments

The nodes representing HTML elements in the DOM must implement, and expose to scripts, the interfaces listed for them in the relevant sections of this specification. This includes HTML elements in XML documents, even when those documents are in another context (e.g. inside an XSLT transform).

Elements in the DOM represent things; that is, they have intrinsic meaning, also known as semantics.

For example, an ol element represents an ordered list.

The basic interface, from which all the HTML elements' interfaces inherit, and which must be used by elements that have no additional requirements, is the HTMLElement interface.

interface HTMLElement : Element {
  // DOM tree accessors
  NodeList getElementsByClassName(in DOMString classNames);

  // dynamic markup insertion
           attribute DOMString innerHTML;
           attribute DOMString outerHTML;
  void insertAdjacentHTML(in DOMString position, in DOMString text);

  // metadata attributes
           attribute DOMString id;
           attribute DOMString title;
           attribute DOMString lang;
           attribute DOMString dir;
           attribute DOMString className;
  readonly attribute DOMTokenList classList;
  readonly attribute DOMStringMap dataset;

  // user interaction
           attribute boolean hidden;
  void click();
  void scrollIntoView();
  void scrollIntoView(in boolean top);
           attribute long tabIndex;
  void focus();
  void blur();
           attribute DOMString accessKey;
  readonly attribute DOMString accessKeyLabel;
           attribute boolean draggable;
           attribute DOMString contentEditable;
  readonly attribute boolean isContentEditable;
           attribute HTMLMenuElement contextMenu;
           attribute DOMString spellcheck;

  // command API
  readonly attribute DOMString commandType;
  readonly attribute DOMString label;
  readonly attribute DOMString icon;
  readonly attribute boolean disabled;
  readonly attribute boolean checked;

  // styling
  readonly attribute CSSStyleDeclaration style;

  // event handler IDL attributes
           attribute Function onabort;
           attribute Function onblur;
           attribute Function oncanplay;
           attribute Function oncanplaythrough;
           attribute Function onchange;
           attribute Function onclick;
           attribute Function oncontextmenu;
           attribute Function ondblclick;
           attribute Function ondrag;
           attribute Function ondragend;
           attribute Function ondragenter;
           attribute Function ondragleave;
           attribute Function ondragover;
           attribute Function ondragstart;
           attribute Function ondrop;
           attribute Function ondurationchange;
           attribute Function onemptied;
           attribute Function onended;
           attribute Function onerror;
           attribute Function onfocus;
           attribute Function onformchange;
           attribute Function onforminput;
           attribute Function oninput;
           attribute Function oninvalid;
           attribute Function onkeydown;
           attribute Function onkeypress;
           attribute Function onkeyup;
           attribute Function onload;
           attribute Function onloadeddata;
           attribute Function onloadedmetadata;
           attribute Function onloadstart;
           attribute Function onmousedown;
           attribute Function onmousemove;
           attribute Function onmouseout;
           attribute Function onmouseover;
           attribute Function onmouseup;
           attribute Function onmousewheel;
           attribute Function onpause;
           attribute Function onplay;
           attribute Function onplaying;
           attribute Function onprogress;
           attribute Function onratechange;
           attribute Function onreadystatechange;
           attribute Function onscroll;
           attribute Function onseeked;
           attribute Function onseeking;
           attribute Function onselect;
           attribute Function onshow;
           attribute Function onstalled;
           attribute Function onsubmit;
           attribute Function onsuspend;
           attribute Function ontimeupdate;
           attribute Function onvolumechange;
           attribute Function onwaiting;
};

interface HTMLUnknownElement : HTMLElement { };

The HTMLElement interface holds methods and attributes related to a number of disparate features, and the members of this interface are therefore described in various different sections of this specification.

The HTMLUnknownElement interface must be used for HTML elements that are not defined by this specification (or other applicable specifications).

2.2.3 Global attributes

Status: Last call for comments

The following attributes are common to and may be specified on all HTML elements (even those not defined in this specification):


The following event handler content attributes may be specified on any HTML element:

The attributes marked with an asterisk have a different meaning when specified on body elements as those elements expose event handlers of the Window object with the same names.

While these attributes apply to all elements, they are not useful on all elements. For example, only media elements will ever receive a volumechange event fired by the user agent.


Custom data attributes (e.g. data-foldername or data-msgid) can be specified on any HTML element, to store custom data specific to the page.


In HTML documents, elements in the HTML namespace may have an xmlns attribute specified, if, and only if, it has the exact value "http://www.w3.org/1999/xhtml". This does not apply to XML documents.

In HTML, the xmlns attribute has absolutely no effect. It is basically a talisman. It is allowed merely to make migration to and from XHTML mildly easier. When parsed by an HTML parser, the attribute ends up in no namespace, not the "http://www.w3.org/2000/xmlns/" namespace like namespace declaration attributes in XML do.

In XML, an xmlns attribute is part of the namespace declaration mechanism, and an element cannot actually have an xmlns attribute in no namespace specified.


To enable assistive technology products to expose a more fine-grained interface than is otherwise possible with HTML elements and attributes, a set of annotations for assistive technology products can be specified.

2.2.3.1 The id attribute

Status: Last call for comments

The id attribute specifies its element's unique identifier (ID). The value must be unique amongst all the IDs in the element's home subtree and must contain at least one character. The value must not contain any space characters.

An element's unique identifier can be used for a variety of purposes, most notably as a way to link to specific parts of a document using fragment identifiers, as a way to target an element when scripting, and as a way to style a specific element from CSS.

If the value is not the empty string, user agents must associate the element with the given value (exactly, including any space characters) for the purposes of ID matching within the element's home subtree (e.g. for selectors in CSS or for the getElementById() method in the DOM).

Identifiers are opaque strings. Particular meanings should not be derived from the value of the id attribute.

This specification doesn't preclude an element having multiple IDs, if other mechanisms (e.g. DOM Core methods) can set an element's ID in a way that doesn't conflict with the id attribute.

The id IDL attribute must reflect the id content attribute.

2.2.3.2 The title attribute

Status: Last call for comments

The title attribute represents advisory information for the element, such as would be appropriate for a tooltip. On a link, this could be the title or a description of the target resource; on an image, it could be the image credit or a description of the image; on a paragraph, it could be a footnote or commentary on the text; on a citation, it could be further information about the source; and so forth. The value is text.

If this attribute is omitted from an element, then it implies that the title attribute of the nearest ancestor HTML element with a title attribute set is also relevant to this element. Setting the attribute overrides this, explicitly stating that the advisory information of any ancestors is not relevant to this element. Setting the attribute to the empty string indicates that the element has no advisory information.

If the title attribute's value contains U+000A LINE FEED (LF) characters, the content is split into multiple lines. Each U+000A LINE FEED (LF) character represents a line break.

Caution is advised with respect to the use of newlines in title attributes.

For instance, the following snippet actually defines an abbreviation's expansion with a line break in it:

<p>My logs show that there was some interest in <abbr title="Hypertext
Transport Protocol">HTTP</abbr> today.</p>

Some elements, such as link, abbr, and input, define additional semantics for the title attribute beyond the semantics described above.


The title IDL attribute must reflect the title content attribute.

2.2.3.3 The lang and xml:lang attributes

Status: Last call for comments

The lang attribute (in no namespace) specifies the primary language for the element's contents and for any of the element's attributes that contain text. Its value must be a valid BCP 47 language code, or the empty string. [BCP47]

The lang attribute in the XML namespace is defined in XML. [XML]

If these attributes are omitted from an element, then the language of this element is the same as the language of its parent element, if any. Setting the attribute to the empty string indicates that the primary language is unknown.

The lang attribute in no namespace may be used on any HTML element.

The lang attribute in the XML namespace may be used on HTML elements in XML documents, as well as elements in other namespaces if the relevant specifications allow it (in particular, MathML and SVG allow lang attributes in the XML namespace to be specified on their elements). If both the lang attribute in no namespace and the lang attribute in the XML namespace are specified on the same element, they must have exactly the same value when compared in an ASCII case-insensitive manner.

Authors must not use the lang attribute in the XML namespace on HTML elements in HTML documents. To ease migration to and from XHTML, authors may specify an attribute in no namespace with no prefix and with the literal localname "xml:lang" on HTML elements in HTML documents, but such attributes must only be specified if a lang attribute in no namespace is also specified, and both attributes must have the same value when compared in an ASCII case-insensitive manner.

The attribute in no namespace with no prefix and with the literal localname "xml:lang" has no effect on language processing.


To determine the language of a node, user agents must look at the nearest ancestor element (including the element itself if the node is an element) that has a lang attribute in the XML namespace set or is an HTML element and has a lang in no namespace attribute set. That attribute specifies the language of the node.

If both the lang attribute in no namespace and the lang attribute in the XML namespace are set on an element, user agents must use the lang attribute in the XML namespace, and the lang attribute in no namespace must be ignored for the purposes of determining the element's language.

If no explicit language is given for any ancestors of the node, including the root element, but there is a document-wide default language set, then that is the language of the node.

If there is no document-wide default language, then language information from a higher-level protocol (such as HTTP), if any, must be used as the final fallback language. In the absence of any language information, and in cases where the higher-level protocol reports multiple languages, the language of the node is unknown (the empty string).

If the resulting value is not a recognized language code, then it must be treated as an unknown language having the given language code, distinct from all other languages. For the purposes of round-tripping or communicating with other services that expect language codes, user agents should pass unknown language codes through unmodified.

Thus, for instance, an element with lang="xyzzy" would be matched by the selector :lang('xyzzy') (e.g. in CSS), but it would not be matched by :lang('abcde'), even though both are equally invalid. Similarly, if a Web browser and screen reader working in unison communicated about the language of the element, the browser would tell the screen reader that the language was "xyzzy", even if it knew it was invalid, just in case the screen reader actually supported a language with that code after all.


User agents may use the element's language to determine proper processing or rendering (e.g. in the selection of appropriate fonts or pronunciations, or for dictionary selection).


The lang IDL attribute must reflect the lang content attribute in no namespace.

2.2.3.4 The xml:base attribute (XML only)

The xml:base attribute is defined in XML Base. [XMLBASE]

The xml:base attribute may be used on elements of XML documents. Authors must not use the xml:base attribute in HTML documents.

2.2.3.5 The dir attribute

Status: Last call for comments

The dir attribute specifies the element's text directionality. The attribute is an enumerated attribute with the keyword ltr mapping to the state ltr, and the keyword rtl mapping to the state rtl. The attribute has no defaults.

The processing of this attribute is primarily performed by the presentation layer. For example, the rendering section in this specification defines a mapping from this attribute to the CSS 'direction' and 'unicode-bidi' properties, and CSS defines rendering in terms of those properties.

The directionality of an element, which is used in particular by the canvas element's text rendering API, is either 'ltr' or 'rtl'. If the user agent supports CSS and the 'direction' property on this element has a computed value of either 'ltr' or 'rtl', then that is the directionality of the element. Otherwise, if the element is being rendered, then the directionality of the element is the directionality used by the presentation layer, potentially determined from the value of the dir attribute on the element. Otherwise, if the element's dir attribute has the state ltr, the element's directionality is 'ltr' (left-to-right); if the attribute has the state rtl, the element's directionality is 'rtl' (right-to-left); and otherwise, the element's directionality is the same as its parent element, or 'ltr' if there is no parent element.


document . dir [ = value ]

Returns the html element's dir attribute's value, if any.

Can be set, to either "ltr" or "rtl", to replace the html element's dir attribute's value.

If there is no html element, returns the empty string and ignores new values.

The dir IDL attribute on an element must reflect the dir content attribute of that element, limited to only known values.

The dir IDL attribute on HTMLDocument objects must reflect the dir content attribute of the html element, if any, limited to only known values. If there is no such element, then the attribute must return the empty string and do nothing on setting.

Authors are strongly encouraged to use the dir attribute to indicate text direction rather than using CSS, since that way their documents will continue to render correctly even in the absence of CSS (e.g. as interpreted by search engines).

2.2.3.6 The class attribute

Status: Last call for comments

Every HTML element may have a class attribute specified.

The attribute, if specified, must have a value that is a set of space-separated tokens representing the various classes that the element belongs to.

The classes that an HTML element has assigned to it consists of all the classes returned when the value of the class attribute is split on spaces. (Duplicates are ignored.)

Assigning classes to an element affects class matching in selectors in CSS, the getElementsByClassName() method in the DOM, and other such features.

There are no additional restrictions on the tokens authors can use in the class attribute, but authors are encouraged to use values that describe the nature of the content, rather than values that describe the desired presentation of the content.


The className and classList IDL attributes must both reflect the class content attribute.

2.2.3.7 The style attribute

Status: Last call for comments

All HTML elements may have the style content attribute set. This is a CSS styling attribute as defined by the CSS Styling Attribute Syntax specification. [CSSATTR]

In user agents that support CSS, the attribute's value must be parsed when the attribute is added or has its value changed, according to the rules given for CSS styling attributes. [CSSATTR]

Documents that use style attributes on any of their elements must still be comprehensible and usable if those attributes were removed.

In particular, using the style attribute to hide and show content, or to convey meaning that is otherwise not included in the document, is non-conforming. (To hide and show content, use the hidden attribute.)


element . style

Returns a CSSStyleDeclaration object for the element's style attribute.

The style IDL attribute must return a CSSStyleDeclaration whose value represents the declarations specified in the attribute, if present. Mutating the CSSStyleDeclaration object must create a style attribute on the element (if there isn't one already) and then change its value to be a value representing the serialized form of the CSSStyleDeclaration object. [CSSOM]

In the following example, the words that refer to colors are marked up using the span element and the style attribute to make those words show up in the relevant colors in visual media.

<p>My sweat suit is <span style="color: green; background:
transparent">green</span> and my eyes are <span style="color: blue;
background: transparent">blue</span>.</p>
2.2.3.8 Embedding custom non-visible data

Status: Last call for comments

A custom data attribute is an attribute in no namespace whose name starts with the string "data-", has at least one character after the hyphen, is XML-compatible, and contains no characters in the range U+0041 to U+005A (LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z).

All attributes on HTML elements in HTML documents get ASCII-lowercased automatically, so the restriction on ASCII uppercase letters doesn't affect such documents.

Custom data attributes are intended to store custom data private to the page or application, for which there are no more appropriate attributes or elements.

These attributes are not intended for use by software that is independent of the site that uses the attributes.

For instance, a site about music could annotate list items representing tracks in an album with custom data attributes containing the length of each track. This information could then be used by the site itself to allow the user to sort the list by track length, or to filter the list for tracks of certain lengths.

<ol>
 <li data-length="2m11s">Beyond The Sea</li>
 ...
</ol>

It would be inappropriate, however, for the user to use generic software not associated with that music site to search for tracks of a certain length by looking at this data.

This is because these attributes are intended for use by the site's own scripts, and are not a generic extension mechanism for publicly-usable metadata.

Every HTML element may have any number of custom data attributes specified, with any value.


element . dataset

Returns a DOMStringMap object for the element's data-* attributes.

The dataset IDL attribute provides convenient accessors for all the data-* attributes on an element. On getting, the dataset IDL attribute must return a DOMStringMap object, associated with the following algorithms, which expose these attributes on their element:

The algorithm for getting the list of name-value pairs
  1. Let list be an empty list of name-value pairs.
  2. For each content attribute on the element whose first five characters are the string "data-", add a name-value pair to list whose name is the attribute's name with the first five character removed and whose value is the attribute's value.
  3. Return list.
The algorithm for setting names to certain values
  1. Let name be the concatenation of the string data- and the name passed to the algorithm.
  2. Let value be the value passed to the algorithm.
  3. Set the value of the attribute with the name name, to the value value, replacing any previous value if the attribute already existed. If setAttribute() would have raised an exception when setting an attribute with the name name, then this must raise the same exception.
The algorithm for deleting names
  1. Let name be the concatenation of the string data- and the name passed to the algorithm.
  2. Remove the attribute with the name name, if such an attribute exists. Do nothing otherwise.

If a Web page wanted an element to represent a space ship, e.g. as part of a game, it would have to use the class attribute along with data-* attributes:

<div class="spaceship" data-id="92432"
     data-weapons="laser 2" data-shields="50%"
     data-x="30" data-y="10" data-z="90">
 <button class="fire"
         onclick="spaceships[this.parentNode.dataset.id].fire()">
  Fire
 </button>
</div>

Authors should carefully design such extensions so that when the attributes are ignored and any associated CSS dropped, the page is still usable.

User agents must not derive any implementation behavior from these attributes or values. Specifications intended for user agents must not define these attributes to have any meaningful values.

JavaScript libraries may use the custom data attributes, as they are considered to be part of the page on which they are used. Authors of libraries that are reused by many authors are encouraged to include their name in the attribute names, to reduce the risk of clashes.

For example, a library called "DoQuery" could use attribute names like data-doquery-range, and a library called "jJo" could use attributes names like data-jjo-range.

2.2.4 Element definitions

Status: Last call for comments

Each element in this specification has a definition that includes the following information:

Categories
A list of categories to which the element belongs. These are used when defining the content models for each element.
Contexts in which this element may be used
A non-normative description of where the element can be used. This information is redundant with the content models of elements that allow this one as a child, and is provided only as a convenience.
Content model
A normative description of what content must be included as children and descendants of the element.
Content attributes
A normative list of attributes that may be specified on the element.
DOM interface
A normative definition of a DOM interface that such elements must implement.

This is then followed by a description of what the element represents, along with any additional normative conformance criteria that may apply to authors and implementations. Examples are sometimes also included.

2.2.5 Content models

Status: Last call for comments

Each element defined in this specification has a content model: a description of the element's expected contents. An HTML element must have contents that match the requirements described in the element's content model.

As noted in the conformance and terminology sections, for the purposes of determining if an element matches its content model or not, CDATASection nodes in the DOM are treated as equivalent to Text nodes, and entity reference nodes are treated as if they were expanded in place.

The space characters are always allowed between elements. User agents represent these characters between elements in the source markup as text nodes in the DOM. Empty text nodes and text nodes consisting of just sequences of those characters are considered inter-element whitespace.

Inter-element whitespace, comment nodes, and processing instruction nodes must be ignored when establishing whether an element's contents match the element's content model or not, and must be ignored when following algorithms that define document and element semantics.

An element A is said to be preceded or followed by a second element B if A and B have the same parent node and there are no other element nodes or text nodes (other than inter-element whitespace) between them.

Authors must not use HTML elements anywhere except where they are explicitly allowed, as defined for each element, or as explicitly required by other specifications. For XML compound documents, these contexts could be inside elements from other namespaces, if those elements are defined as providing the relevant contexts.

The Atom specification defines the Atom content element, when its type attribute has the value xhtml, as requiring that it contains a single HTML div element. Thus, a div element is allowed in that context, even though this is not explicitly normatively stated by this specification. [ATOM]

In addition, HTML elements may be orphan nodes (i.e. without a parent node).

For example, creating a td element and storing it in a global variable in a script is conforming, even though td elements are otherwise only supposed to be used inside tr elements.

var data = {
  name: "Banana",
  cell: document.createElement('td'),
};
2.2.5.1 Kinds of content

Status: Last call for comments

Each element in HTML falls into zero or more categories that group elements with similar characteristics together. The following broad categories are used in this specification:

Some elements also fall into other categories, which are defined in other parts of this specification.

These categories are related as follows:

Sectioning content, heading content, phrasing content, and
  embedded content are all types of flow content. Embedded content is
  also a type of phrasing content.

In addition, certain elements are categorized as form-associated elements and further subcategorized to define their role in various form-related processing models.

Some elements have unique requirements and do not fit into any particular category.

2.2.5.1.1 Metadata content

Status: Last call for comments

Metadata content is content that sets up the presentation or behavior of the rest of the content, or that sets up the relationship of the document with other documents, or that conveys other "out of band" information.

Elements from other namespaces whose semantics are primarily metadata-related (e.g. RDF) are also metadata content.

Thus, in the XML serialization, one can use RDF, like this:

<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:r="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
 <head>
  <title>Hedral's Home Page</title>
  <r:RDF>
   <Person xmlns="http://www.w3.org/2000/10/swap/pim/contact#"
           r:about="http://hedral.example.com/#">
    <fullName>Cat Hedral</fullName>
    <mailbox r:resource="mailto:hedral@damowmow.com"/>
    <personalTitle>Sir</personalTitle>
   </Person>
  </r:RDF>
 </head>
 <body>
  <h1>My home page</h1>
  <p>I like playing with string, I guess. Sister says squirrels are fun
  too so sometimes I follow her to play with them.</p>
 </body>
</html>

This isn't possible in the HTML serialization, however.

2.2.5.1.2 Flow content

Status: Last call for comments

Most elements that are used in the body of documents and applications are categorized as flow content.

As a general rule, elements whose content model allows any flow content should have either at least one descendant text node that is not inter-element whitespace, or at least one descendant element node that is embedded content. For the purposes of this requirement, del elements and their descendants must not be counted as contributing to the ancestors of the del element.

This requirement is not a hard requirement, however, as there are many cases where an element can be empty legitimately, for example when it is used as a placeholder which will later be filled in by a script, or when the element is part of a template and would on most pages be filled in but on some pages is not relevant.

2.2.5.1.3 Sectioning content

Status: Last call for comments

Sectioning content is content that defines the scope of headings and footers.

Each sectioning content element potentially has a heading and an outline. See the section on headings and sections for further details.

There are also certain elements that are sectioning roots. These are distinct from sectioning content, but they can also have an outline.

2.2.5.1.4 Heading content

Status: Last call for comments

Heading content defines the header of a section (whether explicitly marked up using sectioning content elements, or implied by the heading content itself).

2.2.5.1.5 Phrasing content

Status: Last call for comments

Phrasing content is the text of the document, as well as elements that mark up that text at the intra-paragraph level. Runs of phrasing content form paragraphs.

As a general rule, elements whose content model allows any phrasing content should have either at least one descendant text node that is not inter-element whitespace, or at least one descendant element node that is embedded content. For the purposes of this requirement, nodes that are descendants of del elements must not be counted as contributing to the ancestors of the del element.

Most elements that are categorized as phrasing content can only contain elements that are themselves categorized as phrasing content, not any flow content.

Text, in the context of content models, means text nodes. Text is sometimes used as a content model on its own, but is also phrasing content, and can be inter-element whitespace (if the text nodes are empty or contain just space characters).

2.2.5.1.6 Embedded content

Status: Last call for comments

Embedded content is content that imports another resource into the document, or content from another vocabulary that is inserted into the document.

Elements that are from namespaces other than the HTML namespace and that convey content but not metadata, are embedded content for the purposes of the content models defined in this specification. (For example, MathML, or SVG.)

Some embedded content elements can have fallback content: content that is to be used when the external resource cannot be used (e.g. because it is of an unsupported format). The element definitions state what the fallback is, if any.

2.2.5.1.7 Interactive content

Status: Last call for comments

Interactive content is content that is specifically intended for user interaction.

Certain elements in HTML have an activation behavior, which means that the user can activate them. This triggers a sequence of events dependent on the activation mechanism, and normally culminating in a click event followed by a DOMActivate event, as described below.

The user agent should allow the user to manually trigger elements that have an activation behavior, for instance using keyboard or voice input, or through mouse clicks. When the user triggers an element with a defined activation behavior in a manner other than clicking it, the default action of the interaction event must be to run synthetic click activation steps on the element.

When a user agent is to run synthetic click activation steps on an element, the user agent must run pre-click activation steps on the element, then fire a click event at the element. The default action of this click event must be to run post-click activation steps on the element. If the event is canceled, the user agent must run canceled activation steps on the element instead.

Given an element target, the nearest activatable element is the element returned by the following algorithm:

  1. If target has a defined activation behavior, then return target and abort these steps.

  2. If target has a parent element, then set target to that parent element and return to the first step.

  3. Otherwise, there is no nearest activatable element.

When a pointing device is clicked, the user agent must run these steps:

  1. Let e be the nearest activatable element of the element designated by the user, if any.

  2. If there is an element e, run pre-click activation steps on it.

  3. Dispatch the required click event.

    If there is an element e, then the default action of the click event must be to run post-click activation steps on element e.

    If there is an element e but the event is canceled, the user agent must run canceled activation steps on element e.

The above doesn't happen for arbitrary synthetic events dispatched by author script. However, the click() method can be used to make it happen programmatically.

When a user agent is to run pre-click activation steps on an element, it must run the pre-click activation steps defined for that element, if any.

When a user agent is to run post-click activation steps on an element, the user agent must fire a simple event named DOMActivate that is cancelable at that element. The default action of this event must be to run final activation steps on that element. If the event is canceled, the user agent must run canceled activation steps on the element instead.

When a user agent is to run canceled activation steps on an element, it must run the canceled activation steps defined for that element, if any.

When a user agent is to run final activation steps on an element, it must run the activation behavior defined for that element. Activation behaviors can refer to the click and DOMActivate events that were fired by the steps above leading up to this point.

2.2.5.2 Transparent content models

Status: Last call for comments

Some elements are described as transparent; they have "transparent" in the description of their content model.

When a content model includes a part that is "transparent", those parts must not contain content that would not be conformant if all transparent elements in the tree were replaced, in their parent element, by the children in the "transparent" part of their content model, retaining order.

Consider the following markup fragment:

<p>Hello <a href="world.html"><em>wonderful</em> world</a>!</p>

Its DOM looks like the following:

The content model of the a element is transparent. To see if its contents are conforming, therefore, the element is replaced by its contents:

Since that is conforming, the contents of the a are conforming in the original fragment.

When a transparent element has no parent, then the part of its content model that is "transparent" must instead be treated as accepting any flow content.

2.2.5.3 Paragraphs

Status: Last call for comments

The term paragraph as defined in this section is distinct from (though related to) the p element defined later. The paragraph concept defined here is used to describe how to interpret documents.

A paragraph is typically a run of phrasing content that forms a block of text with one or more sentences that discuss a particular topic, as in typography, but can also be used for more general thematic grouping. For instance, an address is also a paragraph, as is a part of a form, a byline, or a stanza in a poem.

In the following example, there are two paragraphs in a section. There is also a heading, which contains phrasing content that is not a paragraph. Note how the comments and inter-element whitespace do not form paragraphs.

<section>
  <h1>Example of paragraphs</h1>
  This is the <em>first</em> paragraph in this example.
  <p>This is the second.</p>
  <!-- This is not a paragraph. -->
</section>

Paragraphs in flow content are defined relative to what the document looks like without the a, ins, del, and map elements complicating matters, since those elements, with their hybrid content models, can straddle paragraph boundaries, as shown in the first two examples below.

Generally, having elements straddle paragraph boundaries is best avoided. Maintaining such markup can be difficult.

The following example takes the markup from the earlier example and puts ins and del elements around some of the markup to show that the text was changed (though in this case, the changes admittedly don't make much sense). Notice how this example has exactly the same paragraphs as the previous one, despite the ins and del elements — the ins element straddles the heading and the first paragraph, and the del element straddles the boundary between the two paragraphs.

<section>
  <ins><h1>Example of paragraphs</h1>
  This is the <em>first</em> paragraph in</ins> this example<del>.
  <p>This is the second.</p></del>
  <!-- This is not a paragraph. -->
</section>

Let view be a view of the DOM that replaces all a, ins, del, and map elements in the document with their contents. Then, in view, for each run of sibling phrasing content nodes uninterrupted by other types of content, in an element that accepts content other than phrasing content as well as phrasing content, let first be the first node of the run, and let last be the last node of the run. For each such run that consists of at least one node that is neither embedded content nor inter-element whitespace, a paragraph exists in the original DOM from immediately before first to immediately after last. (Paragraphs can thus span across a, ins, del, and map elements.)

Conformance checkers may warn authors of cases where they have paragraphs that overlap each other (this can happen with object, video, audio, and canvas elements).

A paragraph is also formed explicitly by p elements.

The p element can be used to wrap individual paragraphs when there would otherwise not be any content other than phrasing content to separate the paragraphs from each other.

In the following example, the link spans half of the first paragraph, all of the heading separating the two paragraphs, and half of the second paragraph. It straddles the paragraphs and the heading.

<aside>
 Welcome!
 <a href="about.html">
  This is home of...
  <h1>The Falcons!</h1>
  The Lockheed Martin multirole jet fighter aircraft!
 </a>
 This page discusses the F-16 Fighting Falcon's innermost secrets.
</aside>

Here is another way of marking this up, this time showing the paragraphs explicitly, and splitting the one link element into three:

<aside>
 <p>Welcome! <a href="about.html">This is home of...</a></p>
 <h1><a href="about.html">The Falcons!</a></h1>
 <p><a href="about.html">The Lockheed Martin multirole jet
 fighter aircraft!</a> This page discusses the F-16 Fighting
 Falcon's innermost secrets.</p>
</aside>

It is possible for paragraphs to overlap when using certain elements that define fallback content. For example, in the following section:

<section>
 <h1>My Cats</h1>
 You can play with my cat simulator.
 <object data="cats.sim">
  To see the cat simulator, use one of the following links:
  <ul>
   <li><a href="cats.sim">Download simulator file</a>
   <li><a href="http://sims.example.com/watch?v=LYds5xY4INU">Use online simulator</a>
  </ul>
  Alternatively, upgrade to the Mellblom Browser.
 </object>
 I'm quite proud of it.
</section>

There are five paragraphs:

  1. The paragraph that says "You can play with my cat simulator. object I'm quite proud of it.", where object is the object element.
  2. The paragraph that says "To see the cat simulator, use one of the following links:".
  3. The paragraph that says "Download simulator file".
  4. The paragraph that says "Use online simulator".
  5. The paragraph that says "Alternatively, upgrade to the Mellblom Browser.".

The first paragraph is overlapped by the other four. A user agent that supports the "cats.sim" resource will only show the first one, but a user agent that shows the fallback will confusingly show the first sentence of the first paragraph as if it was in the same paragraph as the second one, and will show the last paragraph as if it was at the start of the second sentence of the first paragraph.

To avoid this confusion, explicit p elements can be used.

2.2.6 Annotations for assistive technology products (ARIA)

Authors may use the ARIA role and aria-* attributes on HTML elements, in accordance with the requirements described in the ARIA specifications, except where these conflict with the strong native semantics described below. These exceptions are intended to prevent authors from making assistive technology products report nonsensical states that do not represent the actual state of the document. [ARIA]

User agents are required to implement ARIA semantics on all HTML elements, as defined in the ARIA specifications. The implicit ARIA semantics defined below must be recognised by implementations. [ARIAIMPL]

The following table defines the strong native semantics and corresponding implicit ARIA semantics that apply to HTML elements. Each language feature (element or attribute) in a cell in the first column implies the ARIA semantics (role, states, and/or properties) given in the cell in the second column of the same row. Authors must not set the ARIA role and aria-* attributes in a manner that conflicts with the semantics described in the following table. When multiple rows apply to an element, the role from the last row to define a role must be applied, and the states and properties from all the rows must be combined.

Language feature Strong native semantics and implied ARIA semantics
a element that represents a hyperlink link role
address element contentinfo role
area element that represents a hyperlink link role
button element button role
datalist element listbox role, with the aria-multiselectable property set to "false"
footer element contentinfo role
h1 element that does not have an hgroup ancestor heading role, with the aria-level property set to the element's outline depth
h2 element that does not have an hgroup ancestor heading role, with the aria-level property set to the element's outline depth
h3 element that does not have an hgroup ancestor heading role, with the aria-level property set to the element's outline depth
h4 element that does not have an hgroup ancestor heading role, with the aria-level property set to the element's outline depth
h5 element that does not have an hgroup ancestor heading role, with the aria-level property set to the element's outline depth
h6 element that does not have an hgroup ancestor heading role, with the aria-level property set to the element's outline depth
hgroup element heading role, with the aria-level property set to the element's outline depth
hr element separator role
img element whose alt attribute's value is empty presentation role
input element with a type attribute in the Button state button role
input element with a type attribute in the Checkbox state checkbox role, with the aria-checked state set to "mixed" if the element's indeterminate IDL attribute is true, or "true" if the element's checkedness is true, or "false" otherwise
input element with a type attribute in the Color state No role
input element with a type attribute in the Date state No role, with the aria-readonly state set to "true" if the element has a readonly attribute
input element with a type attribute in the Date and Time state No role, with the aria-readonly state set to "true" if the element has a readonly attribute
input element with a type attribute in the Local Date and Time state No role, with the aria-readonly state set to "true" if the element has a readonly attribute
input element with a type attribute in the E-mail state with no suggestions source element textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
input element with a type attribute in the File Upload state button role
input element with a type attribute in the Hidden state No role
input element with a type attribute in the Image Button state button role
input element with a type attribute in the Month state No role, with the aria-readonly state set to "true" if the element has a readonly attribute
input element with a type attribute in the Number state spinbutton role, with the aria-readonly state set to "true" if the element has a readonly attribute, the aria-valuemax property set to the element's maximum, the aria-valuemin property set to the element's minimum, and, if the result of applying the rules for parsing floating point number values to the element's value is a number, with the aria-valuenow property set to that number
input element with a type attribute in the Password state textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
input element with a type attribute in the Radio Button state radio role, with the aria-checked state set to "true" if the element's checkedness is true, or "false" otherwise
input element with a type attribute in the Range state slider role, with the aria-valuemax property set to the element's maximum, the aria-valuemin property set to the element's minimum, and the aria-valuenow property set to the result of applying the rules for parsing floating point number values to the element's value, if that that results in a number, or the default value otherwise
input element with a type attribute in the Reset Button state button role
input element with a type attribute in the Search state with no suggestions source element textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
input element with a type attribute in the Submit Button state button role
input element with a type attribute in the Telephone state with no suggestions source element textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
input element with a type attribute in the Text state with no suggestions source element textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
input element with a type attribute in the Text, Search, Telephone, URL, or E-mail states with a suggestions source element combobox role, with the aria-owns property set to the same value as the list attribute, and the aria-readonly state set to "true" if the element has a readonly attribute
input element with a type attribute in the Time state No role, with the aria-readonly state set to "true" if the element has a readonly attribute
input element with a type attribute in the URL state with no suggestions source element textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
input element with a type attribute in the Week state No role, with the aria-readonly state set to "true" if the element has a readonly attribute
link element that represents a hyperlink link role
menu element with a type attribute in the context menu state No role
menu element with a type attribute in the list state menu role
menu element with a type attribute in the toolbar state toolbar role
nav element navigation role
option element that is in a list of options or that represents a suggestion in a datalist element option role, with the aria-selected state set to "true" if the element's selectedness is true, or "false" otherwise.
progress element progressbar role, with, if the progress bar is determinate, the aria-valuemax property set to the maximum value of the progress bar, the aria-valuemin property set to zero, and the aria-valuenow property set to the current value of the progress bar
select element with a multiple attribute listbox role, with the aria-multiselectable property set to "true"
select element with no multiple attribute listbox role, with the aria-multiselectable property set to "false"
td element gridcell role, with the aria-labelledby property set to the value of the headers attribute, if any
textarea element textbox role, with the aria-multiline property set to "true", and the aria-readonly state set to "true" if the element has a readonly attribute
th element that is neither a column header nor a row header gridcell role, with the aria-labelledby property set to the value of the headers attribute, if any
th element that is a column header columnheader role, with the aria-labelledby property set to the value of the headers attribute, if any
th element that is a row header rowheader role, with the aria-labelledby property set to the value of the headers attribute, if any
tr element row role
An element that defines a command, whose Type facet is "checkbox", and that is a descendant of a menu element whose type attribute in the list state menuitemcheckbox role, with the aria-checked state set to "true" if the command's Checked State facet is true, and "false" otherwise
An element that defines a command, whose Type facet is "command", and that is a descendant of a menu element whose type attribute in the list state menuitem role
An element that defines a command, whose Type facet is "radio", and that is a descendant of a menu element whose type attribute in the list state menuitemradio role, with the aria-checked state set to "true" if the command's Checked State facet is true, and "false" otherwise
Elements that are disabled The aria-disabled state set to "true"
Elements that are required The aria-required state set to "true"

Some HTML elements have native semantics that can be overridden. The following table lists these elements and their implicit ARIA semantics, along with the restrictions that apply to those elements. Each language feature (element or attribute) in a cell in the first column implies, unless otherwise overriden, the ARIA semantic (role, state, or property) given in the cell in the second column of the same row, but this semantic may be overridden under the conditions listed in the cell in the third column of that row.

Language feature Default implied ARIA semantic Restrictions
article element article role Role must be either article, document, application, or main
aside element note role Role must be either note, complementary, or search
header element No role If specified, role must be banner
li element whose parent is an ol or ul element listitem role Role must be either listitem or treeitem
ol element list role Role must be either list, tree, or directory
output element status role No restrictions
section element region role Role must be either region, document, application, contentinfo, main, search, alert, dialog, alertdialog, status, or log
table element grid role Role must be either grid or treegrid
ul element list role Role must be either list or tree, or directory
The body element document role Role must be either document or application

User agents may apply different defaults than those described in this section in order to expose the semantics of HTML elements in a manner more fine-grained than possible with the above definitions.

Conformance checkers are encouraged to phrase errors such that authors are encouraged to use more appropriate elements rather than remove accessibility annotations. For example, if an a element is marked as having the button role, a conformance checker could say "Either a button element or an input element is required when using the button role" rather than "The button role cannot be used with a elements".

2.3 APIs in HTML documents

Status: Last call for comments

For HTML documents, and for HTML elements in HTML documents, certain APIs defined in DOM Core become case-insensitive or case-changing, as sometimes defined in DOM Core, and as summarized or required below. [DOMCORE]

This does not apply to XML documents or to elements that are not in the HTML namespace despite being in HTML documents.

Element.tagName and Node.nodeName

These attributes must return element names converted to ASCII uppercase, regardless of the case with which they were created.

Document.createElement()

The canonical form of HTML markup is all-lowercase; thus, this method will lowercase the argument before creating the requisite element. Also, the element created must be in the HTML namespace.

This doesn't apply to Document.createElementNS(). Thus, it is possible, by passing this last method a tag name in the wrong case, to create an element that appears to have the same tag name as that of an element defined in this specification when its tagName attribute is examined, but that doesn't support the corresponding interfaces. The "real" element name (unaffected by case conversions) can be obtained from the localName attribute.

Element.setAttribute()
Element.setAttributeNode()

Attribute names are converted to ASCII lowercase.

Specifically: when an attribute is set on an HTML element using Element.setAttribute(), the name argument must be converted to ASCII lowercase before the element is affected; and when an Attr node is set on an HTML element using Element.setAttributeNode(), it must have its name converted to ASCII lowercase before the element is affected.

This doesn't apply to Document.setAttributeNS() and Document.setAttributeNodeNS().

Element.getAttribute()
Element.getAttributeNode()

Attribute names are converted to ASCII lowercase.

Specifically: When the Element.getAttribute() method or the Element.getAttributeNode() method is invoked on an HTML element, the name argument must be converted to ASCII lowercase before the element's attributes are examined.

This doesn't apply to Document.getAttributeNS() and Document.getAttributeNodeNS().

Document.getElementsByTagName()
Element.getElementsByTagName()

HTML elements match by lower-casing the argument before comparison, elements from other namespaces are treated as in XML (case-sensitively).

Specifically, these methods (but not their namespaced counterparts) must compare the given argument in a case-sensitive manner, but when looking at HTML elements, the argument must first be converted to ASCII lowercase.

Thus, in an HTML document with nodes in multiple namespaces, these methods will effectively be both case-sensitive and case-insensitive at the same time.

2.4 Interactions with XPath and XSLT

Status: Last call for comments

Implementations of XPath 1.0 that operate on HTML documents parsed or created in the manners described in this specification (e.g. as part of the document.evaluate() API) must act as if the following edit was applied to the XPath 1.0 specification.

First, remove this paragraph:

A QName in the node test is expanded into an expanded-name using the namespace declarations from the expression context. This is the same way expansion is done for element type names in start and end-tags except that the default namespace declared with xmlns is not used: if the QName does not have a prefix, then the namespace URI is null (this is the same way attribute names are expanded). It is an error if the QName has a prefix for which there is no namespace declaration in the expression context.

Then, insert in its place the following:

A QName in the node test is expanded into an expanded-name using the namespace declarations from the expression context. If the QName has a prefix, then there must be a namespace declaration for this prefix in the expression context, and the corresponding namespace URI is the one that is associated with this prefix. It is an error if the QName has a prefix for which there is no namespace declaration in the expression context.

If the QName has no prefix and the principal node type of the axis is element, then the default element namespace is used. Otherwise if the QName has no prefix, the namespace URI is null. The default element namespace is a member of the context for the XPath expression. The value of the default element namespace when executing an XPath expression through the DOM3 XPath API is determined in the following way:

  1. If the context node is from an HTML DOM, the default element namespace is "http://www.w3.org/1999/xhtml".
  2. Otherwise, the default element namespace URI is null.

This is equivalent to adding the default element namespace feature of XPath 2.0 to XPath 1.0, and using the HTML namespace as the default element namespace for HTML documents. It is motivated by the desire to have implementations be compatible with legacy HTML content while still supporting the changes that this specification introduces to HTML regarding the namespace used for HTML elements, and by the desire to use XPath 1.0 rather than XPath 2.0.

This change is a willful violation of the XPath 1.0 specification, motivated by desire to have implementations be compatible with legacy content while still supporting the changes that this specification introduces to HTML regarding which namespace is used for HTML elements. [XPATH10]


XSLT 1.0 processors outputting to a DOM when the output method is "html" (either explicitly or via the defaulting rule in XSLT 1.0) are affected as follows:

If the transformation program outputs an element in no namespace, the processor must, prior to constructing the corresponding DOM element node, change the namespace of the element to the HTML namespace, ASCII-lowercase the element's local name, and ASCII-lowercase the names of any non-namespaced attributes on the element.

This requirement is a willful violation of the XSLT 1.0 specification, required because this specification changes the namespaces and case-sensitivity rules of HTML in a manner that would otherwise be incompatible with DOM-based XSLT transformations. (Processors that serialize the output are unaffected.) [XSLT10]

2.5 Dynamic markup insertion

Status: Last call for comments

APIs for dynamically inserting markup into the document interact with the parser, and thus their behavior varies depending on whether they are used with HTML documents (and the HTML parser) or XHTML in XML documents (and the XML parser).

2.5.1 Opening the input stream

Status: Last call for comments

The open() method comes in several variants with different numbers of arguments.

document = document . open( [ type [, replace ] ] )

Causes the Document to be replaced in-place, as if it was a new Document object, but reusing the previous object, which is then returned.

If the type argument is omitted or has the value "text/html", then the resulting Document has an HTML parser associated with it, which can be given data to parse using document.write(). Otherwise, all content passed to document.write() will be parsed as plain text.

If the replace argument is present and has the value "replace", the existing entries in the session history for the Document object are removed.

The method has no effect if the Document is still being parsed.

Throws an INVALID_STATE_ERR exception if the Document is an XML document.

window = document . open( url, name, features [, replace ] )

Works like the window.open() method.

When called with two or fewer arguments, the method must act as follows:

  1. If the Document object is not flagged as an HTML document, throw an INVALID_STATE_ERR exception and abort these steps.
  2. Let type be the value of the first argument, if there is one, or "text/html" otherwise.

  3. Let replace be true if there is a second argument and it is an ASCII case-insensitive match for the value "replace", and false otherwise.

  4. If the document has an active parser that isn't a script-created parser, and the insertion point associated with that parser's input stream is not undefined (that is, it does point to somewhere in the input stream), then the method does nothing. Abort these steps and return the Document object on which the method was invoked.

    This basically causes document.open() to be ignored when it's called in an inline script found during the parsing of data sent over the network, while still letting it have an effect when called asynchronously or on a document that is itself being spoon-fed using these APIs.

  5. Release the storage mutex.

  6. Prompt to unload the Document object. If the user refused to allow the document to be unloaded, then these steps must be aborted.

  7. Unload the Document object, with the recycle parameter set to true.

  8. If the document has an active parser, then abort that parser, and throw away any pending content in the input stream.

  9. Unregister all event listeners registered on the Document node and its descendants.

  10. Remove any tasks associated with the Document in any task source.

  11. Remove all child nodes of the document, without firing any mutation events.

  12. Replace the Document's singleton objects with new instances of those objects. (This includes in particular the Window, Location, History, ApplicationCache, UndoManager, Navigator, and Selection objects, the various BarProp objects, the two Storage objects, and the various HTMLCollection objects. It also includes all the Web IDL prototypes in the JavaScript binding, including the Document object's prototype.)

  13. Change the document's character encoding to UTF-16.

  14. Change the document's address to the entry script's browsing context's active document's address.

  15. Create a new HTML parser and associate it with the document. This is a script-created parser (meaning that it can be closed by the document.open() and document.close() methods, and that the tokenizer will wait for an explicit call to document.close() before emitting an end-of-file token). The encoding confidence is irrelevant.

  16. If the type string contains a U+003B SEMICOLON character (;), remove the first such character and all characters from it up to the end of the string.

    Strip all leading and trailing space characters from type.

    If type is not now an ASCII case-insensitive match for the string "text/html", then act as if the tokenizer had emitted a start tag token with the tag name "pre", then switch the HTML parser's tokenizer to the PLAINTEXT state.

  17. If replace is false, then:

    1. Remove all the entries in the browsing context's session history after the current entry in its Document's History object
    2. Remove any earlier entries that share the same Document
    3. Add a new entry just before the last entry that is associated with the text that was parsed by the previous parser associated with the Document object, as well as the state of the document at the start of these steps. (This allows the user to step backwards in the session history to see the page before it was blown away by the document.open() call.)
  18. Finally, set the insertion point to point at just before the end of the input stream (which at this point will be empty).

  19. Return the Document on which the method was invoked.

When called with three or more arguments, the open() method on the HTMLDocument object must call the open() method on the Window object of the HTMLDocument object, with the same arguments as the original call to the open() method, and return whatever that method returned. If the HTMLDocument object has no Window object, then the method must raise an INVALID_ACCESS_ERR exception.

2.5.2 Closing the input stream

Status: Last call for comments

document . close()

Closes the input stream that was opened by the document.open() method.

Throws an INVALID_STATE_ERR exception if the Document is an XML document.

The close() method must run the following steps:

  1. If the Document object is not flagged as an HTML document, throw an INVALID_STATE_ERR exception and abort these steps.

  2. If there is no script-created parser associated with the document, then abort these steps.

  3. Insert an explicit "EOF" character at the end of the parser's input stream.

  4. If there is a pending parsing-blocking script, then abort these steps.

  5. Run the tokenizer, processing resulting tokens as they are emitted, and stopping when the tokenizer reaches the explicit "EOF" character or spins the event loop.

2.5.3 document.write()

document . write(text...)

Adds the given string(s) to the Document's input stream. If necessary, calls the open() method implicitly first.

This method throws an INVALID_ACCESS_ERR exception when invoked on XML documents.

The document.write(...) method must act as follows:

  1. If the method was invoked on an XML document, throw an INVALID_ACCESS_ERR exception and abort these steps.

  2. If the insertion point is undefined, the open() method must be called (with no arguments) on the document object. If the user refused to allow the document to be unloaded, then these steps must be aborted. Otherwise, the insertion point will point at just before the end of the (empty) input stream.

  3. The string consisting of the concatenation of all the arguments to the method must be inserted into the input stream just before the insertion point.

  4. If there is a pending parsing-blocking script, then the method must now return without further processing of the input stream.

  5. Otherwise, the tokenizer must process the characters that were inserted, one at a time, processing resulting tokens as they are emitted, and stopping when the tokenizer reaches the insertion point or when the processing of the tokenizer is aborted by the tree construction stage (this can happen if a script end tag token is emitted by the tokenizer).

    If the document.write() method was called from script executing inline (i.e. executing because the parser parsed a set of script tags), then this is a reentrant invocation of the parser.

  6. Finally, the method must return.

2.5.4 document.writeln()

document . writeln(text...)

Adds the given string(s) to the Document's input stream, followed by a newline character. If necessary, calls the open() method implicitly first.

This method throws an INVALID_ACCESS_ERR exception when invoked on XML documents.

The document.writeln(...) method, when invoked, must act as if the document.write() method had been invoked with the same argument(s), plus an extra argument consisting of a string containing a single line feed character (U+000A).

2.5.5 innerHTML

Status: Last call for comments

The innerHTML IDL attribute represents the markup of the node's contents.

document . innerHTML [ = value ]

Returns a fragment of HTML or XML that represents the Document.

Can be set, to replace the Document's contents with the result of parsing the given string.

In the case of XML documents, will throw an INVALID_STATE_ERR if the Document cannot be serialized to XML, and a SYNTAX_ERR if the given string is not well-formed.

element . innerHTML [ = value ]

Returns a fragment of HTML or XML that represents the element's contents.

Can be set, to replace the contents of the element with nodes parsed from the given string.

In the case of XML documents, will throw an INVALID_STATE_ERR if the element cannot be serialized to XML, and a SYNTAX_ERR if the given string is not well-formed.

On getting, if the node's document is an HTML document, then the attribute must return the result of running the HTML fragment serialization algorithm on the node; otherwise, the node's document is an XML document, and the attribute must return the result of running the XML fragment serialization algorithm on the node instead (this might raise an exception instead of returning a string).

On setting, the following steps must be run:

  1. If the node's document is an HTML document: Invoke the HTML fragment parsing algorithm.

    If the node's document is an XML document: Invoke the XML fragment parsing algorithm.

    In either case, the algorithm must be invoked with the string being assigned into the innerHTML attribute as the input. If the node is an Element node, then, in addition, that element must be passed as the context element.

    If this raises an exception, then abort these steps.

    Otherwise, let new children be the nodes returned.

  2. If the attribute is being set on a Document node, and that document has an active parser, then abort that parser.

  3. Remove the child nodes of the node whose innerHTML attribute is being set, firing appropriate mutation events.

  4. If the attribute is being set on a Document node, let target document be that Document node. Otherwise, the attribute is being set on an Element node; let target document be the ownerDocument of that Element.

  5. Set the ownerDocument of all the nodes in new children to the target document.

  6. Append all the new children nodes to the node whose innerHTML attribute is being set, preserving their order, and firing mutation events as if a DocumentFragment containing the new children had been inserted.

2.5.6 outerHTML

Status: Last call for comments

The outerHTML IDL attribute represents the markup of the element and its contents.

element . outerHTML [ = value ]

Returns a fragment of HTML or XML that represents the element and its contents.

Can be set, to replace the element with nodes parsed from the given string.

In the case of XML documents, will throw an INVALID_STATE_ERR if the element cannot be serialized to XML, and a SYNTAX_ERR if the given string is not well-formed.

Throws a NO_MODIFICATION_ALLOWED_ERR exception if the parent of the element is the Document node.

On getting, if the node's document is an HTML document, then the attribute must return the result of running the HTML fragment serialization algorithm on a fictional node whose only child is the node on which the attribute was invoked; otherwise, the node's document is an XML document, and the attribute must return the result of running the XML fragment serialization algorithm on that fictional node instead (this might raise an exception instead of returning a string).

On setting, the following steps must be run:

  1. Let target be the element whose outerHTML attribute is being set.

  2. If target has no parent node, then abort these steps. There would be no way to obtain a reference to the nodes created even if the remaining steps were run.

  3. If target's parent node is a Document object, throw a NO_MODIFICATION_ALLOWED_ERR exception and abort these steps.

  4. Let parent be target's parent node, unless that is a DocumentFragment node, in which case let parent be an arbitrary body element.

  5. If target's document is an HTML document: Invoke the HTML fragment parsing algorithm.

    If target's document is an XML document: Invoke the XML fragment parsing algorithm.

    In either case, the algorithm must be invoked with the string being assigned into the outerHTML attribute as the input, and parent as the context element.

    If this raises an exception, then abort these steps.

    Otherwise, let new children be the nodes returned.

  6. Set the ownerDocument of all the nodes in new children to target's document.

  7. Remove target from its parent node, firing mutation events as appropriate, and then insert in its place all the new children nodes, preserving their order, and again firing mutation events as if a DocumentFragment containing the new children had been inserted.

2.5.7 insertAdjacentHTML()

element . insertAdjacentHTML(position, text)

Parses the given string text as HTML or XML and inserts the resulting nodes into the tree in the position given by the position argument, as follows:

"beforebegin"
Before the element itself.
"afterbegin"
Just inside the element, before its first child.
"beforeend"
Just inside the element, after its last child.
"afterend"
After the element itself.

Throws a SYNTAX_ERR exception if the arguments have invalid values (e.g., in the case of XML documents, if the given string is not well-formed).

Throws a NO_MODIFICATION_ALLOWED_ERR exception if the given position isn't possible (e.g. inserting elements after the root element of a Document).

The insertAdjacentHTML(position, text) method, when invoked, must run the following algorithm:

  1. Let position and text be the method's first and second arguments, respectively.

  2. Let target be the element on which the method was invoked.

  3. Use the first matching item from this list:

    If position is an ASCII case-insensitive match for the string "beforebegin"
    If position is an ASCII case-insensitive match for the string "afterend"

    If target has no parent node, then abort these steps.

    If target's parent node is a Document object, then throw a NO_MODIFICATION_ALLOWED_ERR exception and abort these steps.

    Otherwise, let context be the parent node of target.

    If position is an ASCII case-insensitive match for the string "afterbegin"
    If position is an ASCII case-insensitive match for the string "beforeend"

    Let context be the same as target.

    Otherwise

    Throw a SYNTAX_ERR exception.

  4. If target's document is an HTML document: Invoke the HTML fragment parsing algorithm.

    If target's document is an XML document: Invoke the XML fragment parsing algorithm.

    In either case, the algorithm must be invoked with text as the input, and the element selected in by the previous step as the context element.

    If this raises an exception, then abort these steps.

    Otherwise, let new children be the nodes returned.

  5. Set the ownerDocument of all the nodes in new children to target's document.

  6. Use the first matching item from this list:

    If position is an ASCII case-insensitive match for the string "beforebegin"

    Insert all the new children nodes immediately before target.

    If position is an ASCII case-insensitive match for the string "afterbegin"

    Insert all the new children nodes before the first child of target, if there is one. If there is no such child, append them all to target.

    If position is an ASCII case-insensitive match for the string "beforeend"

    Append all the new children nodes to target.

    If position is an ASCII case-insensitive match for the string "afterend"

    Insert all the new children nodes immediately after target.

    The new children nodes must be inserted in a manner that preserves their order and fires mutation events as if a DocumentFragment containing the new children had been inserted.

3 The elements of HTML

3.1 The root element

Status: Last call for comments

3.1.1 The html element

Status: Last call for comments

Categories
None.
Contexts in which this element may be used:
As the root element of a document.
Wherever a subdocument fragment is allowed in a compound document.
Content model:
A head element followed by a body element.
Content attributes:
Global attributes
manifest
DOM interface:
interface HTMLHtmlElement : HTMLElement {};

The html element represents the root of an HTML document.

The manifest attribute gives the address of the document's application cache manifest, if there is one. If the attribute is present, the attribute's value must be a valid URL.

The manifest attribute only has an effect during the early stages of document load. Changing the attribute dynamically thus has no effect (and thus, no DOM API is provided for this attribute).

For the purposes of application cache selection, later base elements cannot affect the resolving of relative URLs in manifest attributes, as the attributes are processed before those elements are seen.

The html element in the following example declares that the document's language is English.

<!DOCTYPE html>
<html lang="en">
<head>
<title>Swapping Songs</title>
</head>
<body>
<h1>Swapping Songs</h1>
<p>Tonight I swapped some of the songs I wrote with some friends, who
gave me some of the songs they wrote. I love sharing my music.</p>
</body>
</html>

3.2 Document metadata

Status: Last call for comments

3.2.1 The head element

Status: Last call for comments

Categories
None.
Contexts in which this element may be used:
As the first element in an html element.
Content model:
One or more elements of metadata content, of which exactly one is a title element.
Content attributes:
Global attributes
DOM interface:
interface HTMLHeadElement : HTMLElement {};

The head element represents a collection of metadata for the Document.

The collection of metadata in a head element can be large or small. Here is an example of a very short one:

<!doctype html>
<html>
 <head>
  <title>A document with a short head</title>
 </head>
 <body>
 ...

Here is an example of a longer one:

<!DOCTYPE HTML>
<HTML>
 <HEAD>
  <META CHARSET="UTF-8">
  <BASE HREF="http://www.example.com/">
  <TITLE>An application with a long head</TITLE>
  <LINK REL="STYLESHEET" HREF="default.css">
  <LINK REL="STYLESHEET ALTERNATE" HREF="big.css" TITLE="Big Text">
  <SCRIPT SRC="support.js"></SCRIPT>
  <META NAME="APPLICATION-NAME" CONTENT="Long headed application">
 </HEAD>
 <BODY>
 ...

3.2.2 The title element

Status: Last call for comments

Categories
Metadata content.
Contexts in which this element may be used:
In a head element containing no other title elements.
Content model:
Text.
Content attributes:
Global attributes
DOM interface:
interface HTMLTitleElement : HTMLElement {
           attribute DOMString text;
};

The title element represents the document's title or name. Authors should use titles that identify their documents even when they are used out of context, for example in a user's history or bookmarks, or in search results. The document's title is often different from its first heading, since the first heading does not have to stand alone when taken out of context.

There must be no more than one title element per document.

title . text [ = value ]

Returns the contents of the element, ignoring child nodes that aren't text nodes.

Can be set, to replace the element's children with the given value.

The IDL attribute text must return a concatenation of the contents of all the text nodes that are direct children of the title element (ignoring any other nodes such as comments or elements), in tree order. On setting, it must act the same way as the textContent IDL attribute.

Here are some examples of appropriate titles, contrasted with the top-level headings that might be used on those same pages.

  <title>Introduction to The Mating Rituals of Bees</title>
    ...
  <h1>Introduction</h1>
  <p>This companion guide to the highly successful
  <cite>Introduction to Medieval Bee-Keeping</cite> book is...

The next page might be a part of the same site. Note how the title describes the subject matter unambiguously, while the first heading assumes the reader knows what the context is and therefore won't wonder if the dances are Salsa or Waltz:

  <title>Dances used during bee mating rituals</title>
    ...
  <h1>The Dances</h1>

The string to use as the document's title is given by the document.title IDL attribute. User agents should use the document's title when referring to the document in their user interface.

3.2.3 The base element

Status: Last call for comments

Categories
Metadata content.
Contexts in which this element may be used:
In a head element containing no other base elements.
Content model:
Empty.
Content attributes:
Global attributes
href
target
DOM interface:
interface HTMLBaseElement : HTMLElement {
           attribute DOMString href;
           attribute DOMString target;
};

The base element allows authors to specify the document base URL for the purposes of resolving relative URLs, and the name of the default browsing context for the purposes of following hyperlinks. The element does not represent any content beyond this information.

There must be no more than one base element per document.

A base element must have either an href attribute, a target attribute, or both.

The href content attribute, if specified, must contain a valid URL.

A base element, if it has an href attribute, must come before any other elements in the tree that have attributes defined as taking URLs, except the html element (its manifest attribute isn't affected by base elements).

If there are multiple base elements with href attributes, all but the first are ignored.

The target attribute, if specified, must contain a valid browsing context name or keyword, which specifies which browsing context is to be used as the default when hyperlinks and forms in the Document cause navigation.

A base element, if it has a target attribute, must come before any elements in the tree that represent hyperlinks.

If there are multiple base elements with target attributes, all but the first are ignored.

The href and target IDL attributes must reflect the respective content attributes of the same name.

In this example, a base element is used to set the document base URL:

<!DOCTYPE html>
<html>
    <head>
        <title>This is an example for the &lt;base&gt; element</title>
        <base href="http://www.example.com/news/index.html">
    </head>
    <body>
        <p>Visit the <a href="archives.html">archives</a>.</p>
    </body>
</html>

The link in the above example would be a link to "http://www.example.com/news/archives.html".

Status: Last call for comments

Categories
Metadata content.
Contexts in which this element may be used:
Where metadata content is expected.
In a noscript element that is a child of a head element.
Content model:
Empty.
Content attributes:
Global attributes
href
rel
media
hreflang
type
sizes
Also, the title attribute has special semantics on this element.
DOM interface:
interface HTMLLinkElement : HTMLElement {
           attribute boolean disabled;
           attribute DOMString href;
           attribute DOMString rel;
  readonly attribute DOMTokenList relList;
           attribute DOMString media;
           attribute DOMString hreflang;
           attribute DOMString type;
           attribute DOMString sizes;
};
HTMLLinkElement implements LinkStyle;

The link element allows authors to link their document to other resources.

The destination of the link(s) is given by the href attribute, which must be present and must contain a valid URL. If the href attribute is absent, then the element does not define a link.

A link element must have rel attribute.

The types of link indicated (the relationships) are given by the value of the rel attribute, which, if present, must have a value that is a set of space-separated tokens. The allowed values and their meanings are defined in a later section. If the rel attribute is absent, or if the values used are not allowed according to the definitions in this specification, then the element does not define a link.

Two categories of links can be created using the link element. Links to external resources are links to resources that are to be used to augment the current document, and hyperlink links are links to other documents. The link types section defines whether a particular link type is an external resource or a hyperlink. One element can create multiple links (of which some might be external resource links and some might be hyperlinks); exactly which and how many links are created depends on the keywords given in the rel attribute. User agents must process the links on a per-link basis, not a per-element basis.

Each link is handled separately. For instance, if there are two link elements with rel="stylesheet", they each count as a separate external resource, and each is affected by its own attributes independently.

The exact behavior for links to external resources depends on the exact relationship, as defined for the relevant link type. Some of the attributes control whether or not the external resource is to be applied (as defined below). For external resources that are represented in the DOM (for example, style sheets), the DOM representation must be made available even if the resource is not applied. To obtain the resource, the user agent must resolve the URL given by the href attribute, relative to the element, and then fetch the resulting absolute URL. User agents may opt to only try to obtain such resources when they are needed, instead of pro-actively fetching all the external resources that are not applied.

The semantics of the protocol used (e.g. HTTP) must be followed when fetching external resources. (For example, redirects will be followed and 404 responses will cause the external resource to not be applied.)

Once the attempts to obtain the resource and its critical subresources are complete, the user agent must, if the loads were successful, queue a task to fire a simple event named load at the link element, or, if the resource or one of its critical subresources failed to completely load for any reason (e.g. DNS error, HTTP 404 response, a connection being prematurely closed, unsupported Content-Type), queue a task to fire a simple event named error at the link element. Non-network errors in processing the resource or its subresources (e.g. CSS parse errors, PNG decoding errors) are not failures for the purposes of this paragraph.

The task source for these tasks is the DOM manipulation task source.

The element must delay the load event of the element's document until all the attempts to obtain the resource and its critical subresources are complete. (Resources that the user agent has not yet attempted to obtain, e.g. because it is waiting for the resource to be needed, do not delay the load event.)

Which resources are considered critical or not is defined by the relevant specification. For CSS resources, only @import rules introduce critical subresources; other resources, e.g. fonts or backgrounds, are not.


Interactive user agents may provide users with a means to follow the hyperlinks created using the link element, somewhere within their user interface. The exact interface is not defined by this specification, but it could include the following information (obtained from the element's attributes, again as defined below), in some form or another (possibly simplified), for each hyperlink created with each link element in the document:

User agents could also include other information, such as the type of the resource (as given by the type attribute).

Hyperlinks created with the link element and its rel attribute apply to the whole page. This contrasts with the rel attribute of a and area elements, which indicates the type of a link whose context is given by the link's location within the document.

The media attribute says which media the resource applies to. The value must be a valid media query.

If the link is a hyperlink then the media attribute is purely advisory, and describes for which media the document in question was designed.

However, if the link is an external resource link, then the media attribute is prescriptive. The user agent must apply the external resource to a view when the media attribute's value matches the environment of that view and the other relevant conditions apply, and must not apply it otherwise.

The external resource might have further restrictions defined within that limit its applicability. For example, a CSS style sheet might have some @media blocks. This specification does not override such further restrictions or requirements.

The default, if the media attribute is omitted, is "all", meaning that by default links apply to all media.

The hreflang attribute on the link element has the same semantics as the hreflang attribute on hyperlink elements.

The type attribute gives the MIME type of the linked resource. It is purely advisory. The value must be a valid MIME type, optionally with parameters.

For external resource links, the type attribute is used as a hint to user agents so that they can avoid fetching resources they do not support. If the attribute is present, then the user agent must assume that the resource is of the given type (even if that is not a valid MIME type, e.g. the empty string). If the attribute is omitted, but the external resource link type has a default type defined, then the user agent must assume that the resource is of that type. If the UA does not support the given MIME type for the given link relationship, then the UA should not obtain the resource; if the UA does support the given MIME type for the given link relationship, then the UA should obtain the resource. If the attribute is omitted, and the external resource link type does not have a default type defined, but the user agent would obtain the resource if the type was known and supported, then the user agent should obtain the resource under the assumption that it will be supported.

User agents must not consider the type attribute authoritative — upon fetching the resource, user agents must not use the type attribute to determine its actual type. Only the actual type (as defined in the next paragraph) is used to determine whether to apply the resource, not the aforementioned assumed type.

The stylesheet link type defines rules for processing the resource's Content-Type metadata.

Once the user agent has established the type of the resource, the user agent must apply the resource if it is of a supported type and the other relevant conditions apply, and must ignore the resource otherwise.

If a document contains style sheet links labeled as follows:

<link rel="stylesheet" href="A" type="text/plain">
<link rel="stylesheet" href="B" type="text/css">
<link rel="stylesheet" href="C">

...then a compliant UA that supported only CSS style sheets would fetch the B and C files, and skip the A file (since text/plain is not the MIME type for CSS style sheets).

For files B and C, it would then check the actual types returned by the server. For those that are sent as text/css, it would apply the styles, but for those labeled as text/plain, or any other type, it would not.

If one of the two files was returned without a Content-Type metadata, or with a syntactically incorrect type like Content-Type: "null", then the default type for stylesheet links would kick in. Since that default type is text/css, the style sheet would nonetheless be applied.

The title attribute gives the title of the link. With one exception, it is purely advisory. The value is text. The exception is for style sheet links, where the title attribute defines alternative style sheet sets.

The title attribute on link elements differs from the global title attribute of most other elements in that a link without a title does not inherit the title of the parent element: it merely has no title.

The sizes attribute is used with the icon link type. The attribute must not be specified on link elements that do not have a rel attribute that specifies the icon keyword.

Some versions of HTTP defined a Link: header, to be processed like a series of link elements. If supported, for the purposes of ordering links defined by HTTP headers must be assumed to come before any links in the document, in the order that they were given in the HTTP entity header. (URIs in these headers are to be processed and resolved according to the rules given in HTTP; the rules of this specification don't apply.) [HTTP] [WEBLINK]

The IDL attributes href, rel, media, hreflang, and type, and sizes each must reflect the respective content attributes of the same name.

The IDL attribute relList must reflect the rel content attribute.

The IDL attribute disabled only applies to style sheet links. When the link element defines a style sheet link, then the disabled attribute behaves as defined for the alternative style sheets DOM. For all other link elements it always return false and does nothing on setting.

The LinkStyle interface is also implemented by this element; the styling processing model defines how. [CSSOM]

Here, a set of link elements provide some style sheets:

<!-- a persistent style sheet -->
<link rel="stylesheet" href="default.css">

<!-- the preferred alternate style sheet -->
<link rel="stylesheet" href="green.css" title="Green styles">

<!-- some alternate style sheets -->
<link rel="alternate stylesheet" href="contrast.css" title="High contrast">
<link rel="alternate stylesheet" href="big.css" title="Big fonts">
<link rel="alternate stylesheet" href="wide.css" title="Wide screen">

The following example shows how you can specify versions of the page that use alternative formats, are aimed at other languages, and that are intended for other media:

<link rel=alternate href="/en/html" hreflang=en type=text/html title="English HTML">
<link rel=alternate href="/fr/html" hreflang=fr type=text/html title="French HTML">
<link rel=alternate href="/en/html/print" hreflang=en type=text/html media=print title="English HTML (for printing)">
<link rel=alternate href="/fr/html/print" hreflang=fr type=text/html media=print title="French HTML (for printing)">
<link rel=alternate href="/en/pdf" hreflang=en type=application/pdf title="English PDF">
<link rel=alternate href="/fr/pdf" hreflang=fr type=application/pdf title="French PDF">

3.2.5 The meta element

Status: Last call for comments

Categories
Metadata content.
Contexts in which this element may be used:
If the charset attribute is present, or if the element's http-equiv attribute is in the Encoding declaration state: in a head element.
If the http-equiv attribute is present but not in the Encoding declaration state: in a head element.
If the http-equiv attribute is present but not in the Encoding declaration state: in a noscript element that is a child of a head element.
If the name attribute is present: where metadata content is expected.
Content model:
Empty.
Content attributes:
Global attributes
name
http-equiv
content
charset
DOM interface:
interface HTMLMetaElement : HTMLElement {
           attribute DOMString name;
           attribute DOMString httpEquiv;
           attribute DOMString content;
};

The meta element represents various kinds of metadata that cannot be expressed using the title, base, link, style, and script elements.

The meta element can represent document-level metadata with the name attribute, pragma directives with the http-equiv attribute, and the file's character encoding declaration when an HTML document is serialized to string form (e.g. for transmission over the network or for disk storage) with the charset attribute.

Exactly one of the name, http-equiv, and charset attributes must be specified.

If either name or http-equiv is specified, then the content attribute must also be specified. Otherwise, it must be omitted.

The charset attribute specifies the character encoding used by the document. This is a character encoding declaration. If the attribute is present in an XML document, its value must be an ASCII case-insensitive match for the string "UTF-8" (and the document is therefore forced to use UTF-8 as its encoding).

The charset attribute on the meta element has no effect in XML documents, and is only allowed in order to facilitate migration to and from XHTML.

There must not be more than one meta element with a charset attribute per document.

The content attribute gives the value of the document metadata or pragma directive when the element is used for those purposes. The allowed values depend on the exact context, as described in subsequent sections of this specification.

If a meta element has a name attribute, it sets document metadata. Document metadata is expressed in terms of name/value pairs, the name attribute on the meta element giving the name, and the content attribute on the same element giving the value. The name specifies what aspect of metadata is being set; valid names and the meaning of their values are described in the following sections. If a meta element has no content attribute, then the value part of the metadata name/value pair is the empty string.

The name and content IDL attributes must reflect the respective content attributes of the same name. The IDL attribute httpEquiv must reflect the content attribute http-equiv.

3.2.5.1 Standard metadata names

Status: Last call for comments

This specification defines a few names for the name attribute of the meta element.

Names are case-insensitive, and must be compared in an ASCII case-insensitive manner.

application-name

The value must be a short free-form string giving the name of the Web application that the page represents. If the page is not a Web application, the application-name metadata name must not be used. There must not be more than one meta element with its name attribute set to the value application-name per document. User agents may use the application name in UI in preference to the page's title, since the title might include status messages and the like relevant to the status of the page at a particular moment in time instead of just being the name of the application.

author

The value must be a free-form string giving the name of one of the page's authors.

description

The value must be a free-form string that describes the page. The value must be appropriate for use in a directory of pages, e.g. in a search engine. There must not be more than one meta element with its name attribute set to the value description per document.

generator

The value must be a free-form string that identifies one of the software packages used to generate the document. This value must not be used on hand-authored pages.

Here is what a tool called "Frontweaver" could include in its output, in the page's head element, to identify itself as the tool used to generate the page:

<meta name=generator content="Frontweaver 8.2">
3.2.5.2 Other metadata names

Status: Last call for comments. ISSUE-27 (rel-ownership) blocks progress to Last Call

Extensions to the predefined set of metadata names may be registered in the WHATWG Wiki MetaExtensions page. [WHATWGWIKI]

Anyone is free to edit the WHATWG Wiki MetaExtensions page at any time to add a type. These new names must be specified with the following information:

Keyword

The actual name being defined. The name should not be confusingly similar to any other defined name (e.g. differing only in case).

Brief description

A short non-normative description of what the metadata name's meaning is, including the format the value is required to be in.

Specification
A link to a more detailed description of the metadata name's semantics and requirements. It could be another page on the Wiki, or a link to an external page.
Synonyms

A list of other names that have exactly the same processing requirements. Authors should not use the names defined to be synonyms, they are only intended to allow user agents to support legacy content. Anyone may remove synonyms that are not used in practice; only names that need to be processed as synonyms for compatibility with legacy content are to be registered in this way.

Status

One of the following:

Proposed
The name has not received wide peer review and approval. Someone has proposed it and is, or soon will be, using it.
Ratified
The name has received wide peer review and approval. It has a specification that unambiguously defines how to handle pages that use the name, including when they use it in incorrect ways.
Discontinued
The metadata name has received wide peer review and it has been found wanting. Existing pages are using this metadata name, but new pages should avoid it. The "brief description" and "specification" entries will give details of what authors should use instead, if anything.

If a metadata name is found to be redundant with existing values, it should be removed and listed as a synonym for the existing value.

If a metadata name is registered in the "proposed" state for a period of a month or more without being used or specified, then it may be removed from the registry.

If a metadata name is added with the "proposed" status and found to be redundant with existing values, it should be removed and listed as a synonym for the existing value. If a metadata name is added with the "proposed" status and found to be harmful, then it should be changed to "discontinued" status.

Anyone can change the status at any time, but should only do so in accordance with the definitions above.

Conformance checkers must use the information given on the WHATWG Wiki MetaExtensions page to establish if a value is allowed or not: values defined in this specification or marked as "proposed" or "ratified" must be accepted, whereas values marked as "discontinued" or not listed in either this specification or on the aforementioned page must be rejected as invalid. Conformance checkers may cache this information (e.g. for performance reasons or to avoid the use of unreliable network connectivity).

When an author uses a new metadata name not defined by either this specification or the Wiki page, conformance checkers should offer to add the value to the Wiki, with the details described above, with the "proposed" status.

Metadata names whose values are to be URLs must not be proposed or accepted. Links must be represented using the link element, not the meta element.

3.2.5.3 Pragma directives

Status: Last call for comments

When the http-equiv attribute is specified on a meta element, the element is a pragma directive.

The http-equiv attribute is an enumerated attribute. The following table lists the keywords defined for this attribute. The states given in the first cell of the rows with keywords give the states to which those keywords map.

State Keywords Notes
Content Language content-language Conformance checkers will include a warning
Encoding declaration content-type
Default style default-style
Refresh refresh

When a meta element is inserted into the document, if its http-equiv attribute is present and represents one of the above states, then the user agent must run the algorithm appropriate for that state, as described in the following list:

Content language state (http-equiv="content-language")

This pragma sets the document-wide default language. Until the pragma is successfully processed, there is no document-wide default language.

Conformance checkers will include a warning if this pragma is used. Authors are encouraged to use the lang attribute instead.

  1. If another meta element with an http-equiv attribute in the Content Language state has already been successfully processed (i.e. when it was inserted the user agent processed it and reached the last step of this list of steps), then abort these steps.

  2. If the meta element has no content attribute, or if that attribute's value is the empty string, then abort these steps.

  3. Let input be the value of the element's content attribute.

  4. Let position point at the first character of input.

  5. Skip whitespace.

  6. Collect a sequence of characters that are neither space characters nor a U+002C COMMA character (,).

  7. Let the document-wide default language be the string that resulted from the previous step.

For meta elements with an http-equiv attribute in the Content Language state, the content attribute must have a value consisting of a valid BCP 47 language code. [BCP47]

This pragma is not exactly equivalent to the HTTP Content-Language header, for instance it only supports one language. [HTTP]

Encoding declaration state (http-equiv="content-type")

The Encoding declaration state is just an alternative form of setting the charset attribute: it is a character encoding declaration. This state's user agent requirements are all handled by the parsing section of the specification.

For meta elements with an http-equiv attribute in the Encoding declaration state, the content attribute must have a value that is an ASCII case-insensitive match for a string that consists of: the literal string "text/html;", optionally followed by any number of space characters, followed by the literal string "charset=", followed by the character encoding name of the character encoding declaration.

If the document contains a meta element with an http-equiv attribute in the Encoding declaration state, then the document must not contain a meta element with the charset attribute present.

The Encoding declaration state may be used in HTML documents, but elements with an http-equiv attribute in that state must not be used in XML documents.

Default style state (http-equiv="default-style")

This pragma sets the name of the default alternative style sheet set.

  1. If the meta element has no content attribute, or if that attribute's value is the empty string, then abort these steps.

  2. Set the preferred style sheet set to the value of the element's content attribute. [CSSOM]

Refresh state (http-equiv="refresh")

This pragma acts as timed redirect.

  1. If another meta element with an http-equiv attribute in the Refresh state has already been successfully processed (i.e. when it was inserted the user agent processed it and reached the last step of this list of steps), then abort these steps.

  2. If the meta element has no content attribute, or if that attribute's value is the empty string, then abort these steps.

  3. Let input be the value of the element's content attribute.

  4. Let position point at the first character of input.

  5. Skip whitespace.

  6. Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and parse the resulting string using the rules for parsing non-negative integers. If the sequence of characters collected is the empty string, then no number will have been parsed; abort these steps. Otherwise, let time be the parsed number.

  7. Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9) and U+002E FULL STOP (.). Ignore any collected characters.

  8. Skip whitespace.

  9. Let url be the address of the current page.

  10. If the character in input pointed to by position is a U+003B SEMICOLON (";"), then advance position to the next character. Otherwise, jump to the last step.

  11. Skip whitespace.

  12. If the character in input pointed to by position is a U+0055 LATIN CAPITAL LETTER U character (U) or a U+0075 LATIN SMALL LETTER U character (u), then advance position to the next character. Otherwise, jump to the last step.

  13. If the character in input pointed to by position is a U+0052 LATIN CAPITAL LETTER R character (R) or a U+0072 LATIN SMALL LETTER R character (r), then advance position to the next character. Otherwise, jump to the last step.

  14. If the character in input pointed to by position is s U+004C LATIN CAPITAL LETTER L character (L) or a U+006C LATIN SMALL LETTER L character (l), then advance position to the next character. Otherwise, jump to the last step.

  15. Skip whitespace.

  16. If the character in input pointed to by position is a U+003D EQUALS SIGN ("="), then advance position to the next character. Otherwise, jump to the last step.

  17. Skip whitespace.

  18. If the character in input pointed to by position is either a U+0027 APOSTROPHE character (') or U+0022 QUOTATION MARK character ("), then let quote be that character, and advance position to the next character. Otherwise, let quote be the empty string.

  19. Let url be equal to the substring of input from the character at position to the end of the string.

  20. If quote is not the empty string, and there is a character in url equal to quote, then truncate url at that character, so that it and all subsequent characters are removed.

  21. Strip any trailing space characters from the end of url.

  22. Strip any U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), and U+000D CARRIAGE RETURN (CR) characters from url.

  23. Resolve the url value to an absolute URL, relative to the meta element. If this fails, abort these steps.

  24. Perform one or more of the following steps:

    • Set a timer so that in time seconds, adjusted to take into account user or user agent preferences, if the user has not canceled the redirect, the user agent navigates the document's browsing context to url, with replacement enabled, and with the document's browsing context as the source browsing context.

    • Provide the user with an interface that, when selected, navigates a browsing context to url, with the document's browsing context as the source browsing context.

    • Do nothing.

    In addition, the user agent may, as with anything, inform the user of any and all aspects of its operation, including the state of any timers, the destinations of any timed redirects, and so forth.

For meta elements with an http-equiv attribute in the Refresh state, the content attribute must have a value consisting either of:

In the former case, the integer represents a number of seconds before the page is to be reloaded; in the latter case the integer represents a number of seconds before the page is to be replaced by the page at the given URL.

A news organization's front page could include the following markup in the page's head element, to ensure that the page automatically reloads from the server every five minutes:

<meta http-equiv="Refresh" content="300">

A sequence of pages could be used as an automated slide show by making each page refresh to the next page in the sequence, using markup such as the following:

<meta http-equiv="Refresh" content="20; URL=page4.html">

There must not be more than one meta element with any particular state in the document at a time.

3.2.5.4 Other pragma directives

Status: Last call for comments

Extensions to the predefined set of pragma directives may, under certain conditions, be registered in the WHATWG Wiki PragmaExtensions page. [WHATWGWIKI]

Such extensions must use a name that is identical to an HTTP header registered in the Permanent Message Header Field Registry, and must have behavior identical to that described for the HTTP header. [IANAPERMHEADERS]

Pragma directives corresponding to headers describing metadata, or not requiring specific user agent processing, must not be registered; instead, use metadata names. Pragma directives corresponding to headers that affect the HTTP processing model (e.g. caching) must not be registered, as they would result in HTTP-level behavior being different for user agents that implement HTML than for user agents that do not.

Anyone is free to edit the WHATWG Wiki PragmaExtensions page at any time to add a pragma directive satisfying these conditions. Such registrations must specify the following information:

Keyword

The actual name being defined. The name must match a previously-registered HTTP name with the same requirements.

Brief description

A short non-normative description of the purpose of the pragma directive.

Specification
A link to the specification defining the corresponding HTTP header.

Conformance checkers must use the information given on the WHATWG Wiki PragmaExtensions page to establish if a value is allowed or not: values defined in this specification or listed on the aforementioned page must be accepted, whereas values not listed in either this specification or on the aforementioned page must be rejected as invalid. Conformance checkers may cache this information (e.g. for performance reasons or to avoid the use of unreliable network connectivity).

3.2.5.5 Specifying the document's character encoding

Status: Last call for comments

A character encoding declaration is a mechanism by which the character encoding used to store or transmit a document is specified.

The following restrictions apply to character encoding declarations:

If an HTML document does not start with a BOM, and if its encoding is not explicitly given by Content-Type metadata, then the character encoding used must be an ASCII-compatible character encoding, and, in addition, if that encoding isn't US-ASCII itself, then the encoding must be specified using a meta element with a charset attribute or a meta element with an http-equiv attribute in the Encoding declaration state.

If an HTML document contains a meta element with a charset attribute or a meta element with an http-equiv attribute in the Encoding declaration state, then the character encoding used must be an ASCII-compatible character encoding.

Authors are encouraged to use UTF-8. Conformance checkers may advise authors against using legacy encodings.

Authoring tools should default to using UTF-8 for newly-created documents.

Encodings in which a series of bytes in the range 0x20 to 0x7E can encode characters other than the corresponding characters in the range U+0020 to U+007E represent a potential security vulnerability: a user agent that does not support the encoding (or does not support the label used to declare the encoding, or does not use the same mechanism to detect the encoding of unlabelled content as another user agent) might end up interpreting technically benign plain text content as HTML tags and JavaScript. For example, this applies to encodings in which the bytes corresponding to "<script>" in ASCII can encode a different string. Authors should not use such encodings, which are known to include JIS_C6226-1983, JIS_X0212-1990, HZ-GB-2312, JOHAB (Windows code page 1361), encodings based on ISO-2022, and encodings based on EBCDIC. Furthermore, authors must not use the CESU-8, UTF-7, BOCU-1 and SCSU encodings, which also fall into this category, because these encodings were never intended for use for Web content. [RFC1345] [RFC1842] [RFC1468] [RFC2237] [RFC1554] [RFC1922] [RFC1557] [CESU8] [UTF7] [BOCU1] [SCSU]

Authors should not use UTF-32, as the HTML5 encoding detection algorithms intentionally do not distinguish it from UTF-16. [UNICODE]

Using non-UTF-8 encodings can have unexpected results on form submission and URL encodings, which use the document's character encoding by default.

In XHTML, the XML declaration should be used for inline character encoding information, if necessary.

In HTML, to declare that the character encoding is UTF-8, the author could include the following markup near the top of the document (in the head element):

<meta charset="utf-8">

In XML, the XML declaration would be used instead, at the very top of the markup:

<?xml version="1.0" encoding="utf-8"?>

3.2.6 The style element

Status: Last call for comments

Categories
Metadata content.
If the scoped attribute is present: flow content.
Contexts in which this element may be used:
If the scoped attribute is absent: where metadata content is expected.
If the scoped attribute is absent: in a noscript element that is a child of a head element.
If the scoped attribute is present: where flow content is expected, but before any other flow content other than other style elements and inter-element whitespace.
Content model:
Depends on the value of the type attribute, but must match requirements described in prose below.
Content attributes:
Global attributes
media
type
scoped
Also, the title attribute has special semantics on this element.
DOM interface:
interface HTMLStyleElement : HTMLElement {
           attribute boolean disabled;
           attribute DOMString media;
           attribute DOMString type;
           attribute boolean scoped;
};
HTMLStyleElement implements LinkStyle;

The style element allows authors to embed style information in their documents. The style element is one of several inputs to the styling processing model. The element does not represent content for the user.

If the type attribute is given, it must contain a valid MIME type, optionally with parameters, that designates a styling language. If the attribute is absent, the type defaults to text/css. [RFC2318]

When examining types to determine if they support the language, user agents must not ignore unknown MIME parameters — types with unknown parameters must be assumed to be unsupported. The charset parameter must be treated as an unknown parameter for the purpose of comparing MIME types here.

The media attribute says which media the styles apply to. The value must be a valid media query. The user agent must apply the styles to a view when the media attribute's value matches the environment of that view and the other relevant conditions apply, and must not apply them otherwise.

The styles might be further limited in scope, e.g. in CSS with the use of @media blocks. This specification does not override such further restrictions or requirements.

The default, if the media attribute is omitted, is "all", meaning that by default styles apply to all media.

The scoped attribute is a boolean attribute. If set, it indicates that the styles are intended just for the subtree rooted at the style element's parent element, as opposed to the whole Document.

If the scoped attribute is present, then the user agent must apply the specified style information only to the style element's parent element (if any), and that element's child nodes. Otherwise, the specified styles must, if applied, be applied to the entire document.

The title attribute on style elements defines alternative style sheet sets. If the style element has no title attribute, then it has no title; the title attribute of ancestors does not apply to the style element. [CSSOM]

The title attribute on style elements, like the title attribute on link elements, differs from the global title attribute in that a style block without a title does not inherit the title of the parent element: it merely has no title.

The textContent of a style element must match the style production in the following ABNF, the character set for which is Unicode. [ABNF]

style         = no-c-start *( c-start no-c-end c-end no-c-start )
no-c-start    = <any string that doesn't contain a substring that matches c-start >
c-start       = "<!--"
no-c-end      = <any string that doesn't contain a substring that matches c-end >
c-end         = "-->"

All descendant elements must be processed, according to their semantics, before the style element itself is evaluated. For styling languages that consist of pure text, user agents must evaluate style elements by passing the concatenation of the contents of all the text nodes that are direct children of the style element (not any other nodes such as comments or elements), in tree order, to the style system. For XML-based styling languages, user agents must pass all the child nodes of the style element to the style system.

All URLs found by the styling language's processor must be resolved, relative to the element (or as defined by the styling language), when the processor is invoked.

Once the attempts to obtain the style sheet's critical subresources, if any, are complete, or, if the style sheet has no critical subresources, once the style sheet has been parsed and processed, the user agent must, if the loads were successful or there were none, queue a task to fire a simple event named load at the style element, or, if one of the style sheet's critical subresources failed to completely load for any reason (e.g. DNS error, HTTP 404 response, a connection being prematurely closed, unsupported Content-Type), queue a task to fire a simple event named error at the style element. Non-network errors in processing the style sheet or its subresources (e.g. CSS parse errors, PNG decoding errors) are not failures for the purposes of this paragraph.

The task source for these tasks is the DOM manipulation task source.

The element must delay the load event of the element's document until all the attempts to obtain the style sheet's critical subresources, if any, are complete.

Which resources are considered critical or not is defined by the relevant specification. For CSS resources, only @import rules introduce critical subresources; other resources, e.g. fonts or backgrounds, are not.

This specification does not specify a style system, but CSS is expected to be supported by most Web browsers. [CSS]

The media, type and scoped IDL attributes must reflect the respective content attributes of the same name.

The disabled IDL attribute behaves as defined for the alternative style sheets DOM.

The LinkStyle interface is also implemented by this element; the styling processing model defines how. [CSSOM]

The following document has its emphasis styled as bright red text rather than italics text, while leaving titles of works and Latin words in their default italics. It shows how using appropriate elements enables easier restyling of documents.

<!DOCTYPE html>
<html lang="en-US">
 <head>
  <title>My favorite book</title>
  <style>
   body { color: black; background: white; }
   em { font-style: normal; color: red; }
  </style>
 </head>
 <body>
  <p>My <em>favorite</em> book of all time has <em>got</em> to be
  <cite>A Cat's Life</cite>. It is a book by P. Rahmel that talks
  about the <i lang="la">Felis Catus</i> in modern human society.</p>
 </body>
</html>

3.2.7 Styling

Status: Last call for comments

The link and style elements can provide styling information for the user agent to use when rendering the document. The DOM Styling specification specifies what styling information is to be used by the user agent and how it is to be used. [CSSOM]

The style and link elements implement the LinkStyle interface. [CSSOM]

For style elements, if the user agent does not support the specified styling language, then the sheet attribute of the element's LinkStyle interface must return null. Similarly, link elements that do not represent external resource links that contribute to the styling processing model (i.e. that do not have a stylesheet keyword in their rel attribute), and link elements whose specified resource has not yet been fetched, or is not in a supported styling language, must have their LinkStyle interface's sheet attribute return null.

Otherwise, the LinkStyle interface's sheet attribute must return a StyleSheet object with the following properties: [CSSOM]

The style sheet type

The style sheet type must be the same as the style's specified type. For style elements, this is the same as the type content attribute's value, or text/css if that is omitted. For link elements, this is the Content-Type metadata of the specified resource.

The style sheet location

For link elements, the location must be the result of resolving the URL given by the element's href content attribute, relative to the element, or the empty string if that fails. For style elements, there is no location.

The style sheet media

The media must be the same as the value of the element's media content attribute, or the empty string, if the attribute is omitted.

The style sheet title

The title must be the same as the value of the element's title content attribute, if the attribute is present and has a non-empty value. If the attribute is absent or its value is the empty string, then the style sheet does not have a title (it is the empty string). The title is used for defining alternative style sheet sets.

The style sheet alternate flag

For link elements, true if the link is an alternative stylesheet. In all other cases, false.

The disabled IDL attribute on link and style elements must return false and do nothing on setting, if the sheet attribute of their LinkStyle interface is null. Otherwise, it must return the value of the StyleSheet interface's disabled attribute on getting, and forward the new value to that same attribute on setting.

The rules for handling alternative style sheets are defined in the CSS object model specification. [CSSOM]


Style sheets, whether added by a link element, a style element, an <?xml-stylesheet> PI, an HTTP Link: header, or some other mechanism, have a style sheet ready flag, which is initially unset.

When a style sheet is ready to be applied, its style sheet ready flag must be set. If the style sheet referenced no other resources (e.g. it was an internal style sheet given by a style element with no @import rules), then the style rules must be synchronously made available to script; otherwise, the style rules must only be made available to script once the event loop reaches its "update the rendering" step.

A style sheet in the context of the Document of an HTML parser or XML parser is said to be a style sheet blocking scripts if the element was created by that Document's parser, and the element is either a style element or a link element that was an external resource link that contributes to the styling processing model when the element was created by the parser, and the element's style sheet was enabled when the element was created by the parser, and the element's style sheet ready flag is not yet set, and, the last time the event loop reached step 1, the element was in that Document.

3.3 Scripting

Status: Last call for comments

Scripts allow authors to add interactivity to their documents.

Authors are encouraged to use declarative alternatives to scripting where possible, as declarative mechanisms are often more maintainable, and many users disable scripting.

For example, instead of using script to show or hide a section to show more details, the details element could be used.

Authors are also encouraged to make their applications degrade gracefully in the absence of scripting support.

For example, if an author provides a link in a table header to dynamically resort the table, the link could also be made to function without scripts by requesting the sorted table from the server.

3.3.1 The script element

Status: Last call for comments

Categories
Metadata content.
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where metadata content is expected.
Where phrasing content is expected.
Content model:
If there is no src attribute, depends on the value of the type attribute, but must match script content restrictions.
If there is a src attribute, the element must be either empty or contain only script documentation that also matches script content restrictions.
Content attributes:
Global attributes
src
async
defer
type
charset
DOM interface:
interface HTMLScriptElement : HTMLElement {
           attribute DOMString src;
           attribute boolean async;
           attribute boolean defer;
           attribute DOMString type;
           attribute DOMString charset;
           attribute DOMString text;
};

The script element allows authors to include dynamic script and data blocks in their documents. The element does not represent content for the user.

When used to include dynamic scripts, the scripts may either be embedded inline or may be imported from an external file using the src attribute. If the language is not that described by "text/javascript", then the type attribute must be present, as described below.

When used to include data blocks, the data must be embedded inline, the format of the data must be given using the type attribute, and the src attribute must not be specified.

The type attribute gives the language of the script or format of the data. If the attribute is present, its value must be a valid MIME type, optionally with parameters. The charset parameter must not be specified. (The default, which is used if the attribute is absent, is "text/javascript".)

The src attribute, if specified, gives the address of the external script resource to use. The value of the attribute must be a valid URL identifying a script resource of the type given by the type attribute, if the attribute is present, or of the type "text/javascript", if the attribute is absent. A resource is a script resource of a given type if that type identifies a scripting language and the resource conforms with the requirements of that language's specification.

The charset attribute gives the character encoding of the external script resource. The attribute must not be specified if the src attribute is not present. If the attribute is set, its value must be a valid character encoding name, must be an ASCII case-insensitive match for the preferred MIME name for that encoding, and must match the encoding given in the charset parameter of the Content-Type metadata of the external file, if any. [IANACHARSET]

The async and defer attributes are boolean attributes that indicate how the script should be executed.

There are three possible modes that can be selected using these attributes. If the async attribute is present, then the script will be executed asynchronously, as soon as it is available. If the async attribute is not present but the defer attribute is present, then the script is executed when the page has finished parsing. If neither attribute is present, then the script is fetched and executed immediately, before the user agent continues parsing the page. The exact processing details for these attributes are described below.

The defer attribute may be specified even if the async attribute is specified, to cause legacy Web browsers that only support defer (and not async) to fall back to the defer behavior instead of the synchronous blocking behavior that is the default.

If one or both of the defer and async attributes are specified, the src attribute must also be specified.

Changing the src, type, charset, async, and defer attributes dynamically has no direct effect; these attribute are only used at specific times described below (namely, when the element is inserted into the document).

A script element has several associated pieces of state.

The first is a flag indicating whether or not the script block has been "already started". Initially, script elements must have this flag unset (script blocks, when created, are not "already started"). When a script element is cloned, the "already started" flag, if set, must be propagated to the clone when it is created.

The second is a flag indicating whether the element was "parser-inserted". Initially, script elements must have this flag unset. It is set by the HTML parser and is used to handle document.write() calls.

The third is a flag indicating whether or not the script block is "ready to be parser-executed". Initially, script elements must have this flag unset (script blocks, when created, are not "ready to be parser-executed"). This flag is used only for elements that are also "parser-inserted", to let the parser know when to execute the script.

The fourth and fifth pieces of state are the script block's type and the script block's character encoding. They are determined when the script is run, based on the attributes on the element at that time.

When a script element that is neither marked as having "already started" nor marked as being "parser-inserted" experiences one of the events listed in the following list, the user agent must synchronously run the script element:

Running a script: When a script element is to be run, the user agent must act as follows:

  1. If either:

    • the script element has a type attribute and its value is the empty string, or
    • the script element has no type attribute but it has a language attribute and that attribute's value is the empty string, or
    • the script element has neither a type attribute nor a language attribute, then

    ...let the script block's type for this script element be "text/javascript".

    Otherwise, if the script element has a type attribute, let the script block's type for this script element be the value of that attribute with any leading or trailing sequences of space characters removed.

    Otherwise, the element has a non-empty language attribute; let the script block's type for this script element be the concatenation of the string "text/" followed by the value of the language attribute.

    The language attribute is never conforming, and is always ignored if there is a type attribute present.

  2. If the script element has a charset attribute, then let the script block's character encoding for this script element be the encoding given by the charset attribute.

    Otherwise, let the script block's character encoding for this script element be the same as the encoding of the document itself.

  3. If the script element has a for attribute, then the user agent must abort these steps at this point. The script is not executed.

  4. If scripting is disabled for the script element, or if the user agent does not support the scripting language given by the script block's type for this script element, then the user agent must abort these steps at this point. The script is not executed.

  5. If the element has no src attribute, and its child nodes consist only of comment nodes and empty text nodes, then the user agent must abort these steps at this point. The script is not executed.

  6. The user agent must set the element's "already started" flag.

  7. If the element has a src attribute, then the value of that attribute must be resolved relative to the element, and if that is successful, the specified resource must then be fetched, from the origin of the element's Document.

    For historical reasons, if the URL is a javascript: URL, then the user agent must not, despite the requirements in the definition of the fetching algorithm, actually execute the given script; instead the user agent must act as if it had received an empty HTTP 400 response.

    Once the resource's Content Type metadata is available, if it ever is, apply the algorithm for extracting an encoding from a Content-Type to it. If this returns an encoding, and the user agent supports that encoding, then let the script block's character encoding be that encoding.

    For performance reasons, user agents may start fetching the script as soon as the attribute is set, instead, in the hope that the element will be inserted into the document. Either way, once the element is inserted into the document, the load must have started. If the UA performs such prefetching, but the element is never inserted in the document, or the src attribute is dynamically changed, then the user agent will not execute the script, and the fetching process will have been effectively wasted.

  8. Then, the first of the following options that describes the situation must be followed:

    If the element has a src attribute, and the element has a defer attribute, and the element has been flagged as "parser-inserted", and the element does not have an async attribute

    The element must be added to the end of the list of scripts that will execute when the document has finished parsing.

    The task that the networking task source places on the task queue once the fetching algorithm has completed must set the element's "ready to be parser-executed" flag. The parser will handle executing the script.

    If the element has a src attribute, and the element has been flagged as "parser-inserted", and the element does not have an async attribute

    The element is the pending parsing-blocking script. (There can only be one such script at a time.)

    The task that the networking task source places on the task queue once the fetching algorithm has completed must set the element's "ready to be parser-executed" flag. The parser will handle executing the script.

    If the element does not have a src attribute, but there is a style sheet blocking scripts, and the element has been flagged as "parser-inserted"

    The element is the pending parsing-blocking script. (There can only be one such script at a time.)

    Set the element's "ready to be parser-executed" flag. The parser will handle executing the script.

    If the element has a src attribute

    The element must be added to the end of the list of scripts that will execute as soon as possible.

    The task that the networking task source places on the task queue once the fetching algorithm has completed must execute the script block.

    Otherwise
    The user agent must immediately execute the script block, even if other scripts are already executing.

Fetching an external script must delay the load event of the element's document until the task that is queued by the networking task source once the resource has been fetched (defined above) has been run.

The pending parsing-blocking script is used by the parser.

Executing a script block: When the steps above require that the script block be executed, the user agent must act as follows:

If the load resulted in an error (for example a DNS error, or an HTTP 404 error)

Executing the script block must just consist of firing a simple event named error at the element.

If the load was successful
  1. Initialize the script block's source as follows:

    If the script is from an external file and the script block's type is a text-based language

    The contents of that file, interpreted as string of Unicode characters, are the script source.

    For each of the rows in the following table, starting with the first one and going down, if the file has as many or more bytes available than the number of bytes in the first column, and the first bytes of the file match the bytes given in the first column, then set the script block's character encoding to the encoding given in the cell in the second column of that row, irrespective of any previous value:

    Bytes in Hexadecimal Encoding
    FE FF UTF-16BE
    FF FE UTF-16LE
    EF BB BF UTF-8

    This step looks for Unicode Byte Order Marks (BOMs).

    The file must then be converted to Unicode using the character encoding given by the script block's character encoding.

    If the script is from an external file and the script block's type is an XML-based language

    The external file is the script source. When it is later executed, it must be interpreted in a manner consistent with the specification defining the language given by the script block's type.

    If the script is inline and the script block's type is a text-based language

    The value of the text IDL attribute at the time the "running a script" algorithm was first invoked is the script source.

    If the script is inline and the script block's type is an XML-based language

    The child nodes of the script element at the time the "running a script" algorithm was first invoked are the script source.

  2. Pause until either any applicable style sheets have been fetched and applied, or the user agent has timed out and decided to not wait for those style sheets.

  3. Create a script from the script element node, using the script block's source and the script block's type.

    This is where the script is compiled and actually executed.

  4. Fire a simple event named load at the script element.

The IDL attributes src, type, charset, async, and defer, each must reflect the respective content attributes of the same name.

script . text [ = value ]

Returns the contents of the element, ignoring child nodes that aren't text nodes.

Can be set, to replace the element's children with the given value.

The IDL attribute text must return a concatenation of the contents of all the text nodes that are direct children of the script element (ignoring any other nodes such as comments or elements), in tree order. On setting, it must act the same way as the textContent IDL attribute.

When inserted using the document.write() method, script elements execute (typically synchronously), but when inserted using innerHTML and outerHTML attributes, they do not execute at all.

In this example, two script elements are used. One embeds an external script, and the other includes some data.

<script src="game-engine.js"></script>
<script type="text/x-game-map">
........U.........e
o............A....e
.....A.....AAA....e
.A..AAA...AAAAA...e
</script>

The data in this case might be used by the script to generate the map of a video game. The data doesn't have to be used that way, though; maybe the map data is actually embedded in other parts of the page's markup, and the data block here is just used by the site's search engine to help users who are looking for particular features in their game maps.

The following sample shows how a script element can be used to define a function that is then used by other parts of the document. It also shows how a script element can be used to invoke script while the document is being parsed, in this case to initialize the form's output.

<script>
 function calculate(form) {
   var price = 52000;
   if (form.elements.brakes.checked)
     price += 1000;
   if (form.elements.radio.checked)
     price += 2500;
   if (form.elements.turbo.checked)
     price += 5000;
   if (form.elements.sticker.checked)
     price += 250;
   form.elements.result.value = price;
 }
</script>
<form name="pricecalc" onsubmit="return false">
 <fieldset>
  <legend>Work out the price of your car</legend>
  <p>Base cost: £52000.</p>
  <p>Select additional options:</p>
  <ul>
   <li><label><input type=checkbox name=brakes> Ceramic brakes (£1000)</label></li>
   <li><label><input type=checkbox name=radio> Satellite radio (£2500)</label></li>
   <li><label><input type=checkbox name=turbo> Turbo charger (£5000)</label></li>
   <li><label><input type=checkbox name=sticker> "XZ" sticker (£250)</label></li>
  </ul>
  <p>Total: £<output name=result onformchange="calculate(form)"></output></p>
 </fieldset>
 <script>
  document.forms.pricecalc.dispatchFormChange();
 </script>
</form>
3.3.1.1 Scripting languages

Status: Last call for comments

A user agent is said to support the scripting language if the script block's type is an ASCII case-insensitive match for the MIME type string of a scripting language that the user agent implements.

The following lists some MIME type strings and the languages to which they refer:

"application/ecmascript"
"application/javascript"
"application/x-ecmascript"
"application/x-javascript"
"text/ecmascript"
"text/javascript"
"text/javascript1.0"
"text/javascript1.1"
"text/javascript1.2"
"text/javascript1.3"
"text/javascript1.4"
"text/javascript1.5"
"text/jscript"
"text/livescript"
"text/x-ecmascript"
"text/x-javascript"
JavaScript. [ECMA262]
"text/javascript;e4x=1"
JavaScript with ECMAScript for XML. [ECMA357]

User agents may support other MIME types and other languages.

When examining types to determine if they support the language, user agents must not ignore unknown MIME parameters — types with unknown parameters must be assumed to be unsupported. The charset parameter must be treated as an unknown parameter for the purpose of comparing MIME types here.

3.3.1.2 Restrictions for contents of script elements

Status: Last call for comments

The textContent of a script element must match the script production in the following ABNF, the character set for which is Unicode. [ABNF]

script        = data1 *( escape [ script-start data3 ] "-->" data1 ) [ escape ]
escape        = "<!--" data2 *( script-start data3 script-end data2 )

data1         = <any string that doesn't contain a substring that matches not-data1>
not-data1     = "<!--"             

data2         = <any string that doesn't contain a substring that matches not-data2>
not-data2     = script-start / "-->"  

data3         = <any string that doesn't contain a substring that matches not-data3>
not-data3     = script-end / "-->"

script-start  = lt       s c r i p t tag-end
script-end    = lt slash s c r i p t tag-end

lt            =  %x003C ; U+003C LESS-THAN SIGN character (<)
slash         =  %x002F ; U+002F SOLIDUS character (/)

s             =  %x0053 ; U+0053 LATIN CAPITAL LETTER S
s             =/ %x0073 ; U+0073 LATIN SMALL LETTER S
c             =  %x0043 ; U+0043 LATIN CAPITAL LETTER C
c             =/ %x0063 ; U+0063 LATIN SMALL LETTER C
r             =  %x0052 ; U+0052 LATIN CAPITAL LETTER R
r             =/ %x0072 ; U+0072 LATIN SMALL LETTER R
i             =  %x0049 ; U+0049 LATIN CAPITAL LETTER I
i             =/ %x0069 ; U+0069 LATIN SMALL LETTER I
p             =  %x0050 ; U+0050 LATIN CAPITAL LETTER P
p             =/ %x0070 ; U+0070 LATIN SMALL LETTER P
t             =  %x0054 ; U+0054 LATIN CAPITAL LETTER T
t             =/ %x0074 ; U+0074 LATIN SMALL LETTER T

tag-end       =  %x0009 ; U+0009 CHARACTER TABULATION
tag-end       =/ %x000A ; U+000A LINE FEED (LF)
tag-end       =/ %x000C ; U+000C FORM FEED (FF)
tag-end       =/ %x0020 ; U+0020 SPACE
tag-end       =/ %x002F ; U+002F SOLIDUS (/)
tag-end       =/ %x003E ; U+003E GREATER-THAN SIGN (>)

When a script element contains script documentation, there are further restrictions on the contents of the element, as described in the section below.

3.3.1.3 Inline documentation for external scripts

Status: Last call for comments

If a script element's src attribute is specified, then the contents of the script element, if any, must be such that the value of the text IDL attribute, which is derived from the element's contents, matches the documentation production in the following ABNF, the character set for which is Unicode. [ABNF]

documentation = *( *( space / tab / comment ) [ line-comment ] newline )
comment       = slash star *( not-star / star not-slash ) 1*star slash
line-comment  = slash slash *not-newline

; characters
tab           = %x0009 ; U+0009 TAB
newline       = %x000A ; U+000A LINE FEED (LF)
space         = %x0020 ; U+0020 SPACE
star          = %x002A ; U+002A ASTERISK (*)
slash         = %x002F ; U+002F SOLIDUS (/)
not-newline   = %x0000-0009 / %x000B-10FFFF
                ; a Unicode character other than U+000A LINE FEED (LF)
not-star      = %x0000-0029 / %x002B-10FFFF
                ; a Unicode character other than U+002A ASTERISK (*)
not-slash     = %x0000-002E / %x0030-10FFFF
                ; a Unicode character other than U+002F SOLIDUS (/)

This corresponds to putting the contents of the element in JavaScript comments.

This requirement is in addition to the earlier restrictions on the syntax of contents of script elements.

This allows authors to include documentation, such as license information or API information, inside their documents while still referring to external script files. The syntax is constrained so that authors don't accidentally include what looks like valid script while also providing a src attribute.

<script src="cool-effects.js">
 // create new instances using:
 //    var e = new Effect();
 // start the effect using .play, stop using .stop:
 //    e.play();
 //    e.stop();
</script>

3.3.2 The noscript element

Status: Last call for comments

Categories
Metadata content.
Flow content.
Phrasing content.
Contexts in which this element may be used:
In a head element of an HTML document, if there are no ancestor noscript elements.
Where phrasing content is expected in HTML documents, if there are no ancestor noscript elements.
Content model:
When scripting is disabled, in a head element: in any order, zero or more link elements, zero or more style elements, and zero or more meta elements.
When scripting is disabled, not in a head element: transparent, but there must be no noscript element descendants.
Otherwise: text that conforms to the requirements given in the prose.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The noscript element represents nothing if scripting is enabled, and represents its children if scripting is disabled. It is used to present different markup to user agents that support scripting and those that don't support scripting, by affecting how the document is parsed.

When used in HTML documents, the allowed content model is as follows:

In a head element, if scripting is disabled for the noscript element

The noscript element must contain only link, style, and meta elements.

In a head element, if scripting is enabled for the noscript element

The noscript element must contain only text, except that invoking the HTML fragment parsing algorithm with the noscript element as the context element and the text contents as the input must result in a list of nodes that consists only of link, style, and meta elements that would be conforming if they were children of the noscript element, and no parse errors.

Outside of head elements, if scripting is disabled for the noscript element

The noscript element's content model is transparent, with the additional restriction that a noscript element must not have a noscript element as an ancestor (that is, noscript can't be nested).

Outside of head elements, if scripting is enabled for the noscript element

The noscript element must contain only text, except that the text must be such that running the following algorithm results in a conforming document with no noscript elements and no script elements, and such that no step in the algorithm causes an HTML parser to flag a parse error:

  1. Remove every script element from the document.
  2. Make a list of every noscript element in the document. For every noscript element in that list, perform the following steps:
    1. Let the parent element be the parent element of the noscript element.
    2. Take all the children of the parent element that come before the noscript element, and call these elements the before children.
    3. Take all the children of the parent element that come after the noscript element, and call these elements the after children.
    4. Let s be the concatenation of all the text node children of the noscript element.
    5. Set the innerHTML attribute of the parent element to the value of s. (This, as a side-effect, causes the noscript element to be removed from the document.)
    6. Insert the before children at the start of the parent element, preserving their original relative order.
    7. Insert the after children at the end of the parent element, preserving their original relative order.

All these contortions are required because, for historical reasons, the noscript element is handled differently by the HTML parser based on whether scripting was enabled or not when the parser was invoked.

The noscript element must not be used in XML documents.

The noscript element is only effective in the HTML syntax, it has no effect in the XHTML syntax.

The noscript element has no other requirements. In particular, children of the noscript element are not exempt from form submission, scripting, and so forth, even when scripting is enabled for the element.

In the following example, a noscript element is used to provide fallback for a script.

<form action="calcSquare.php">
 <p>
  <label for=x>Number</label>:
  <input id="x" name="x" type="number">
 </p>
 <script>
  var x = document.getElementById('x');
  var output = document.createElement('p');
  output.textContent = 'Type a number; it will be squared right then!';
  x.form.appendChild(output);
  x.form.onsubmit = function () { return false; }
  x.oninput = function () {
    var v = x.valueAsNumber;
    output.textContent = v + ' squared is ' + v * v;
  };
 </script>
 <noscript>
  <input type=submit value="Calculate Square">
 </noscript>
</form>

When script is disabled, a button appears to do the calculation on the server side. When script is enabled, the value is computed on-the-fly instead.

The noscript element is a blunt instrument. Sometimes, scripts might be enabled, but for some reason the page's script might fail. For this reason, it's generally better to avoid using noscript, and to instead design the script to change the page from being a scriptless page to a scripted page on the fly, as in the next example:

<form action="calcSquare.php">
 <p>
  <label for=x>Number</label>:
  <input id="x" name="x" type="number">
 </p>
 <input id="submit" type=submit value="Calculate Square">
 <script>
  var x = document.getElementById('x');
  var output = document.createElement('p');
  output.textContent = 'Type a number; it will be squared right then!';
  x.form.appendChild(output);
  x.form.onsubmit = function () { return false; }
  x.oninput = function () {
    var v = x.valueAsNumber;
    output.textContent = v + ' squared is ' + v * v;
  };
  var submit = document.getElementById('submit');
  submit.parentNode.removeChild(submit);
 </script>
</form>

The above technique is also useful in XHTML, since noscript is not supported in the XHTML syntax.

3.4 Sections

Status: Last call for comments

3.4.1 The body element

Status: Last call for comments

Categories
Sectioning root.
Contexts in which this element may be used:
As the second element in an html element.
Content model:
Flow content.
Content attributes:
Global attributes
onafterprint
onbeforeprint
onbeforeunload
onblur
onerror
onfocus
onhashchange
onload
onmessage
onoffline
ononline
onpagehide
onpageshow
onpopstate
onredo
onresize
onstorage
onundo
onunload
DOM interface:
interface HTMLBodyElement : HTMLElement {
           attribute Function onafterprint;
           attribute Function onbeforeprint;
           attribute Function onbeforeunload;
           attribute Function onblur;
           attribute Function onerror;
           attribute Function onfocus;
           attribute Function onhashchange;
           attribute Function onload;
           attribute Function onmessage;
           attribute Function onoffline;
           attribute Function ononline;
           attribute Function onpopstate;
           attribute Function onpagehide;
           attribute Function onpageshow;
           attribute Function onredo;
           attribute Function onresize;
           attribute Function onstorage;
           attribute Function onundo;
           attribute Function onunload;
};

The body element represents the main content of the document.

In conforming documents, there is only one body element. The document.body IDL attribute provides scripts with easy access to a document's body element.

Some DOM operations (for example, parts of the drag and drop model) are defined in terms of "the body element". This refers to a particular element in the DOM, as per the definition of the term, and not any arbitrary body element.

The body element exposes as event handler content attributes a number of the event handlers of the Window object. It also mirrors their event handler IDL attributes.

The onblur, onerror, onfocus, and onload event handlers of the Window object, exposed on the body element, shadow the generic event handlers with the same names normally supported by HTML elements.

Thus, for example, a bubbling error event fired on a child of the body element of a Document would first trigger the onerror event handler content attributes of that element, then that of the root html element, and only then would it trigger the onerror event handler content attribute on the body element. This is because the event would bubble from the target, to the body, to the html, to the Document, to the Window, and the event handler on the body is watching the Window not the body. A regular event listener attached to the body using addEventListener(), however, would fire when the event bubbled through the body and not when it reaches the Window object.

This page updates an indicator to show whether or not the user is online:

<!DOCTYPE HTML>
<html>
 <head>
  <title>Online or offline?</title>
  <script>
   function update(online) {
     document.getElementById('status').textContent = 
       online ? 'Online' : 'Offline';
   }
  </script>
 </head>
 <body ononline="update(true)"
       onoffline="update(false)"
       onload="update(navigator.onLine)">
  <p>You are: <span id="status">(Unknown)</span></p>
 </body>
</html>

3.4.2 The section element

Status: Last call for comments

Categories
Flow content.
Sectioning content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The section element represents a generic document or application section. A section, in this context, is a thematic grouping of content, typically with a heading.

Examples of sections would be chapters, the various tabbed pages in a tabbed dialog box, or the numbered sections of a thesis. A Web site's home page could be split into sections for an introduction, news items, contact information.

Authors are encouraged to use the article element instead of the section element when it would make sense to syndicate the contents of the element.

The section element is not a generic container element. When an element is needed for styling purposes or as a convenience for scripting, authors are encouraged to use the div element instead. A general rule is that the section element is appropriate only if the element's contents would be listed explicitly in the document's outline.

In the following example, we see an article (part of a larger Web page) about apples, containing two short sections.

<article>
 <hgroup>
  <h1>Apples</h1>
  <h2>Tasty, delicious fruit!</h2>
 </hgroup>
 <p>The apple is the pomaceous fruit of the apple tree.</p>
 <section>
  <h1>Red Delicious</h1>
  <p>These bright red apples are the most common found in many
  supermarkets.</p>
 </section>
 <section>
  <h1>Granny Smith</h1>
  <p>These juicy, green apples make a great filling for
  apple pies.</p>
 </section>
</article>

Notice how the use of section means that the author can use h1 elements throughout, without having to worry about whether a particular section is at the top level, the second level, the third level, and so on.

Here is a graduation programme with two sections, one for the list of people graduating, and one for the description of the ceremony.

<!DOCTYPE Html>
<Html
 ><Head
   ><Title
     >Graduation Ceremony Summer 2022</Title
   ></Head
 ><Body
   ><H1
     >Graduation</H1
   ><Section
     ><H1
       >Ceremony</H1
     ><P
       >Opening Procession</P
     ><P
       >Speech by Validactorian</P
     ><P
       >Speech by Class President</P
     ><P
       >Presentation of Diplomas</P
     ><P
       >Closing Speech by Headmaster</P
   ></Section
   ><Section
     ><H1
       >Graduates</H1
     ><Ul
       ><Li
         >Molly Carpenter</Li
       ><Li
         >Anastasia Luccio</Li
       ><Li
         >Ebenezar McCoy</Li
       ><Li
         >Karrin Murphy</Li
       ><Li
         >Thomas Raith</Li
       ><Li
         >Susan Rodriguez</Li
     ></Ul
   ></Section
 ></Body
></Html>

3.4.3 The nav element

Status: Last call for comments

Categories
Flow content.
Sectioning content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The nav element represents a section of a page that links to other pages or to parts within the page: a section with navigation links.

Not all groups of links on a page need to be in a nav element — only sections that consist of major navigation blocks are appropriate for the nav element. In particular, it is common for footers to have a short list of links to various pages of a site, such as the terms of service, the home page, and a copyright page. The footer element alone is sufficient for such cases, without a nav element.

User agents (such as screen readers) that are targeted at users who can benefit from navigation information being omitted in the initial rendering, or who can benefit from navigation information being immediately available, can use this element as a way to determine what content on the page to initially skip and/or provide on request.

In the following example, the page has several places where links are present, but only one of those places is considered a navigation section.

<body>
 <header>
  <h1>Wake up sheeple!</h1>
  <p><a href="news.html">News</a> -
     <a href="blog.html">Blog</a> -
     <a href="forums.html">Forums</a></p>
  <p>Last Modified: <time>2009-04-01</time></p>
  <nav>
   <h1>Navigation</h1>
   <ul>
    <li><a href="articles.html">Index of all articles</a></li>
    <li><a href="today.html">Things sheeple need to wake up for today</a></li>
    <li><a href="successes.html">Sheeple we have managed to wake</a></li>
   </ul>
  </nav>
 </header>
 <div>
  <article>
   <header>
    <h1>My Day at the Beach</h1>
   </header>
   <div>
    <p>Today I went to the beach and had a lot of fun.</p>
    ...more content...
   </div>
   <footer>
    <p>Posted <time pubdate datetime="2009-10-10T14:36-08:00">Thursday</time>.</p>
   </footer>
  </article>
  ...more blog posts...
 </div>
 <footer>
  <p>Copyright © 2006 The Example Company</p>
  <p><a href="about.html">About</a> -
     <a href="policy.html">Privacy Policy</a> -
     <a href="contact.html">Contact Us</a></p>
 </footer>
</body>

Notice the div element being used to wrap all the contents of the page other than the header and footer, and all the contents of the blog entry other than its header and footer.

In the following example, there are two nav elements, one for primary navigation around the site, and one for secondary navigation around the page itself.

<body>
 <h1>The Wiki Center Of Exampland</h1>
 <nav>
  <ul>
   <li><a href="/">Home</a></li>
   <li><a href="/events">Current Events</a></li>
   ...more...
  </ul>
 </nav>
 <article>
  <header>
   <h1>Demos in Exampland</h1>
   <p>Written by A. N. Other.</p>
  </header>
  <nav>
   <ul>
    <li><a href="#public">Public demonstrations</a></li>
    <li><a href="#destroy">Demolitions</a></li>
    ...more...
   </ul>
  </nav>
  <div>
   <section id="public">
    <h1>Public demonstrations</h1>
    <p>...more...</p>
   </section>
   <section id="destroy">
    <h1>Demolitions</h1>
    <p>...more...</p>
   </section>
   ...more...
  </div>
  <footer>
   <p><a href="?edit">Edit</a> | <a href="?delete">Delete</a> | <a href="?Rename">Rename</a></p>
  </footer>
 </article>
 <footer>
  <p><small>© copyright 1998 Exampland Emperor</small></p>
 </footer>
</body>

3.4.4 The article element

Status: Last call for comments

Categories
Flow content.
Sectioning content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The article element represents a component of a page that consists of a self-contained composition in a document, page, application, or site and that is intended to be independently distributable or reusable, e.g. in syndication. This could be a forum post, a magazine or newspaper article, a blog entry, a user-submitted comment, an interactive widget or gadget, or any other independent item of content.

When article elements are nested, the inner article elements represent articles that are in principle related to the contents of the outer article. For instance, a blog entry on a site that accepts user-submitted comments could represent the comments as article elements nested within the article element for the blog entry.

Author information associated with an article element (q.v. the address element) does not apply to nested article elements.

When used specifically with content to be redistributed in syndication, the article element is similar in purpose to the entry element in Atom. [ATOM]

The time element's pubdate attribute can be used to provide the publication date for an article element.

This example shows a blog post using the article element:

<article>
 <header>
  <h1>The Very First Rule of Life</h1>
  <p><time pubdate datetime="2009-10-09T14:28-08:00"></time></p>
 </header>
 <p>If there's a microphone anywhere near you, assume it's hot and
 sending whatever you're saying to the world. Seriously.</p>
 <p>...</p>
 <footer>
  <a href="?comments=1">Show comments...</a>
 </footer>
</article>

Here is that same blog post, but showing some of the comments:

<article>
 <header>
  <h1>The Very First Rule of Life</h1>
  <p><time pubdate datetime="2009-10-09T14:28-08:00"></time></p>
 </header>
 <p>If there's a microphone anywhere near you, assume it's hot and
 sending whatever you're saying to the world. Seriously.</p>
 <p>...</p>
 <section>
  <h1>Comments</h1>
  <article>
   <header>
    <p>Posted by: George Washington</p>
    <p><time pubdate datetime="2009-10-10T19:10-08:00"></time></p>
   </header>
   <p>Yeah! Especially when talking about your lobbyist friends!</p>
  </article>
  <article>
   <header>
    <p>Posted by: George Hammond</p>
    <p><time pubdate datetime="2009-10-10T19:15-08:00"></time></p>
   </header>
   <p>Hey, you have the same first name as me.</p>
  </article>
 </section>
</article>

3.4.5 The aside element

Status: Last call for comments

Categories
Flow content.
Sectioning content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The aside element represents a section of a page that consists of content that is tangentially related to the content around the aside element, and which could be considered separate from that content. Such sections are often represented as sidebars in printed typography.

The element can be used for typographical effects like pull quotes or sidebars, for advertising, for groups of nav elements, and for other content that is considered separate from the main content of the page.

It's not appropriate to use the aside element just for parentheticals, since those are part of the main flow of the document.

The following example shows how an aside is used to mark up background material on Switzerland in a much longer news story on Europe.

<aside>
 <h1>Switzerland</h1>
 <p>Switzerland, a land-locked country in the middle of geographic
 Europe, has not joined the geopolitical European Union, though it is
 a signatory to a number of European treaties.</p>
</aside>

The following example shows how an aside is used to mark up a pull quote in a longer article.

...

<p>He later joined a large company, continuing on the same work.
<q>I love my job. People ask me what I do for fun when I'm not at
work. But I'm paid to do my hobby, so I never know what to
answer. Some people wonder what they would do if they didn't have to
work... but I know what I would do, because I was unemployed for a
year, and I filled that time doing exactly what I do now.</q></p>

<aside>
 <q> People ask me what I do for fun when I'm not at work. But I'm
 paid to do my hobby, so I never know what to answer. </q>
</aside>

<p>Of course his work — or should that be hobby? —
isn't his only passion. He also enjoys other pleasures.</p>

...

The following extract shows how aside can be used for blogrolls and other side content on a blog:

<body>
 <header>
  <h1>My wonderful blog</h1>
  <p>My tagline</p>
 </header>
 <aside>
  <!-- this aside contains two sections that are tangentially related
  to the page, namely, links to other blogs, and links to blog posts
  from this blog -->
  <nav>
   <h1>My blogroll</h1>
   <ul>
    <li><a href="http://blog.example.com/">Example Blog</a>
   </ul>
  </nav>
  <nav>
   <h1>Archives</h1>
   <ol reversed>
    <li><a href="/last-post">My last post</a>
    <li><a href="/first-post">My first post</a>
   </ol>
  </nav>
 </aside>
 <aside>
  <!-- this aside is tangentially related to the page also, it
  contains twitter messages from the blog author -->
  <h1>Twitter Feed</h1>
  <blockquote cite="http://twitter.example.net/t31351234">
   <p>I'm on vacation, writing my blog.</p>
  </blockquote>
  <blockquote cite="http://twitter.example.net/t31219752">
   <p>I'm going to go on vacation soon.</p>
  </blockquote>
 </aside>
 <article>
  <!-- this is a blog post -->
  <h1>My last post</h1>
  <p>This is my last post.</p>
  <footer>
   <p><a href="/last-post" rel=bookmark>Permalink</a>
  </footer>
 </article>
 <article>
  <!-- this is also a blog post -->
  <h1>My first post</h1>
  <p>This is my first post.</p>
  <aside>
   <!-- this aside is about the blog post, since it's inside the
   <article> element; it would be wrong, for instance, to put the
   blogroll here, since the blogroll isn't really related to this post
   specifically, only to the page as a whole -->
   <h1>Posting</h1>
   <p>While I'm thinking about it, I wanted to say something about
   posting. Posting is fun!</p>
  </aside>
  <footer>
   <p><a href="/first-post" rel=bookmark>Permalink</a>
  </footer>
 </article>
 <footer>
  <nav>
   <a href="/archives">Archives</a> —
   <a href="/about">About me</a> —
   <a href="/copyright">Copyright</a>
  </nav>
 </footer>
</body>

3.4.6 The h1, h2, h3, h4, h5, and h6 elements

Categories
Flow content.
Heading content.
formatBlock candidate.
Contexts in which this element may be used:
As a child of an hgroup element.
Where flow content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
interface HTMLHeadingElement : HTMLElement {};

These elements represent headings for their sections.

The semantics and meaning of these elements are defined in the section on headings and sections.

These elements have a rank given by the number in their name. The h1 element is said to have the highest rank, the h6 element has the lowest rank, and two elements with the same name have equal rank.

These two snippets are equivalent:

<body>
<h1>Let's call it a draw(ing surface)</h1>
<h2>Diving in</h2>
<h2>Simple shapes</h2>
<h2>Canvas coordinates</h2>
<h3>Canvas coordinates diagram</h3>
<h2>Paths</h2>
</body>
<body>
 <h1>Let's call it a draw(ing surface)</h1>
 <section>
  <h1>Diving in</h1>
 </section>
 <section>
  <h1>Simple shapes</h1>
 </section>
 <section>
  <h1>Canvas coordinates</h1>
  <section>
   <h1>Canvas coordinates diagram</h1>
  </section>
 </section>
 <section>
  <h1>Paths</h1>
 </section>
</body>

3.4.7 The hgroup element

Status: Last call for comments

Categories
Flow content.
Heading content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
One or more h1, h2, h3, h4, h5, and/or h6 elements.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The hgroup element represents the heading of a section. The element is used to group a set of h1h6 elements when the heading has multiple levels, such as subheadings, alternative titles, or taglines.

For the purposes of document summaries, outlines, and the like, the text of hgroup elements is defined to be the text of the highest ranked h1h6 element descendant of the hgroup element, if there are any such elements, and the first such element if there are multiple elements with that rank. If there are no such elements, then the text of the hgroup element is the empty string.

Other elements of heading content in the hgroup element indicate subheadings or subtitles.

The rank of an hgroup element is the rank of the highest-ranked h1h6 element descendant of the hgroup element, if there are any such elements, or otherwise the same as for an h1 element (the highest rank).

The section on headings and sections defines how hgroup elements are assigned to individual sections.

Here are some examples of valid headings. In each case, the emphasized text represents the text that would be used as the heading in an application extracting heading data and ignoring subheadings.

<hgroup>
 <h1>The reality dysfunction</h1>
 <h2>Space is not the only void</h2>
</hgroup>
<hgroup>
 <h1>Dr. Strangelove</h1>
 <h2>Or: How I Learned to Stop Worrying and Love the Bomb</h2>
</hgroup>

The point of using hgroup in these examples is to mask the h2 element (which acts as a secondary title) from the outline algorithm.

3.4.8 The header element

Status: Last call for comments

Categories
Flow content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content, but with no header or footer element descendants.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The header element represents a group of introductory or navigational aids.

A header element is intended to usually contain the section's heading (an h1h6 element or an hgroup element), but this is not required. The header element can also be used to wrap a section's table of contents, a search form, or any relevant logos.

Here are some sample headers. This first one is for a game:

<header>
 <p>Welcome to...</p>
 <h1>Voidwars!</h1>
</header>

The following snippet shows how the element can be used to mark up a specification's header:

<header>
 <hgroup>
  <h1>Scalable Vector Graphics (SVG) 1.2</h1>
  <h2>W3C Working Draft 27 October 2004</h2>
 </hgroup>
 <dl>
  <dt>This version:</dt>
  <dd><a href="http://www.w3.org/TR/2004/WD-SVG12-20041027/">http://www.w3.org/TR/2004/WD-SVG12-20041027/</a></dd>
  <dt>Previous version:</dt>
  <dd><a href="http://www.w3.org/TR/2004/WD-SVG12-20040510/">http://www.w3.org/TR/2004/WD-SVG12-20040510/</a></dd>
  <dt>Latest version of SVG 1.2:</dt>
  <dd><a href="http://www.w3.org/TR/SVG12/">http://www.w3.org/TR/SVG12/</a></dd>
  <dt>Latest SVG Recommendation:</dt>
  <dd><a href="http://www.w3.org/TR/SVG/">http://www.w3.org/TR/SVG/</a></dd>
  <dt>Editor:</dt>
  <dd>Dean Jackson, W3C, <a href="mailto:dean@w3.org">dean@w3.org</a></dd>
  <dt>Authors:</dt>
  <dd>See <a href="#authors">Author List</a></dd>
 </dl>
 <p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notic ...
</header>

The header element is not sectioning content; it doesn't introduce a new section.

In this example, the page has a page heading given by the h1 element, and two subsections whose headings are given by h2 elements. The content after the header element is still part of the last subsection started in the header element, because the header element doesn't take part in the outline algorithm.

<body>
 <header>
  <h1>Little Green Guys With Guns</h1>
  <nav>
   <ul>
    <li><a href="/games">Games</a>
    <li><a href="/forum">Forum</a>
    <li><a href="/download">Download</a>
   </ul>
  </nav>
  <h2>Important News</h2> <!-- this starts a second subsection -->
  <!-- this is part of the subsection entitled "Important News" -->
  <p>To play today's games you will need to update your client.</p>
  <h2>Games</h2> <!-- this starts a third subsection -->
 </header>
 <p>You have three active games:</p>
 <!-- this is still part of the subsection entitled "Games" -->
 ...

Status: Last call for comments

Categories
Flow content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content, but with no header or footer element descendants.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The footer element represents a footer for its nearest ancestor sectioning content or sectioning root element. A footer typically contains information about its section such as who wrote it, links to related documents, copyright data, and the like.

Contact information for the author or editor of a section belongs in an address element, possibly itself inside a footer.

Footers don't necessarily have to appear at the end of a section, though they usually do.

When the footer element contains entire sections, they represent appendices, indexes, long colophons, verbose license agreements, and other such content.

The footer element is not sectioning content; it doesn't introduce a new section.

When the nearest ancestor sectioning content or sectioning root element is the body element, then it applies to the whole page.

Here is a page with two footers, one at the top and one at the bottom, with the same content:

<body>
 <footer><a href="../">Back to index...</a></footer>
 <hgroup>
  <h1>Lorem ipsum</h1>
  <h2>The ipsum of all lorems</h2>
 </hgroup>
 <p>A dolor sit amet, consectetur adipisicing elit, sed do eiusmod
 tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim
 veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex
 ea commodo consequat. Duis aute irure dolor in reprehenderit in
 voluptate velit esse cillum dolore eu fugiat nulla
 pariatur. Excepteur sint occaecat cupidatat non proident, sunt in
 culpa qui officia deserunt mollit anim id est laborum.</p>
 <footer><a href="../">Back to index...</a></footer>
</body>

Here is an example which shows the footer element being used both for a site-wide footer and for a section footer.

<!DOCTYPE HTML>
<HTML><HEAD>
<TITLE>The Ramblings of a Scientist</TITLE>
<BODY>
<H1>The Ramblings of a Scientist</H1>
<ARTICLE>
 <H1>Episode 15</H1>
 <VIDEO SRC="/fm/015.ogv" CONTROLS AUTOBUFFER>
  <P><A HREF="/fm/015.ogv">Download video</A>.</P>
 </VIDEO>
 <FOOTER> <!-- footer for article -->
  <P>Published <TIME PUBDATE DATETIME="2009-10-21T18:26-07:00"></TIME></P>
 </FOOTER>
</ARTICLE>
<ARTICLE>
 <H1>My Favorite Trains</H1>
 <P>I love my trains. My favorite train of all time is a Köf.</P>
 <P>It is fun to see them pull some coal cars because they look so
 dwarfed in comparison.</P>
 <FOOTER> <!-- footer for article -->
  <P>Published <TIME PUBDATE DATETIME="2009-09-15T14:54-07:00"></TIME></P>
 </FOOTER>
</ARTICLE>
<FOOTER> <!-- site wide footer -->
 <NAV>
  <P><A HREF="/credits.html">Credits</A> —
     <A HREF="/tos.html">Terms of Service</A> —
     <A HREF="/index.html">Blog Index</A></P>
 </NAV>
 <P>Copyright © 2009 Gordon Freeman</P>
</FOOTER>
</BODY>
</HTML>

3.4.10 The address element

Status: Last call for comments

Categories
Flow content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content, but with no heading content descendants, no sectioning content descendants, and no header, footer, or address element descendants.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The address element represents the contact information for its nearest article or body element ancestor. If that is the body element, then the contact information applies to the document as a whole.

For example, a page at the W3C Web site related to HTML might include the following contact information:

<ADDRESS>
 <A href="../People/Raggett/">Dave Raggett</A>,
 <A href="../People/Arnaud/">Arnaud Le Hors</A>,
 contact persons for the <A href="Activity">W3C HTML Activity</A>
</ADDRESS>

The address element must not be used to represent arbitrary addresses (e.g. postal addresses), unless those addresses are in fact the relevant contact information. (The p element is the appropriate element for marking up postal addresses in general.)

The address element must not contain information other than contact information.

For example, the following is non-conforming use of the address element:

<ADDRESS>Last Modified: 1999/12/24 23:37:50</ADDRESS>

Typically, the address element would be included along with other information in a footer element.

The contact information for a node node is a collection of address elements defined by the first applicable entry from the following list:

If node is an article element
If node is a body element

The contact information consists of all the address elements that have node as an ancestor and do not have another body or article element ancestor that is a descendant of node.

If node has an ancestor element that is an article element
If node has an ancestor element that is a body element

The contact information of node is the same as the contact information of the nearest article or body element ancestor, whichever is nearest.

If node's Document has a body element

The contact information of node is the same as the contact information the body element of the Document.

Otherwise

There is no contact information for node.

User agents may expose the contact information of a node to the user, or use it for other purposes, such as indexing sections based on the sections' contact information.

3.4.11 Headings and sections

Status: Last call for comments

The h1h6 elements and the hgroup element are headings.

The first element of heading content in an element of sectioning content represents the heading for that section. Subsequent headings of equal or higher rank start new (implied) sections, headings of lower rank start implied subsections that are part of the previous one. In both cases, the element represents the heading of the implied section.

Sectioning content elements are always considered subsections of their nearest ancestor element of sectioning content, regardless of what implied sections other headings may have created.

Certain elements are said to be sectioning roots, including blockquote and td elements. These elements can have their own outlines, but the sections and headings inside these elements do not contribute to the outlines of their ancestors.

For the following fragment:

<body>
 <h1>Foo</h1>
 <h2>Bar</h2>
 <blockquote>
  <h3>Bla</h3>
 </blockquote>
 <p>Baz</p>
 <h2>Quux</h2>
 <section>
  <h3>Thud</h3>
 </section>
 <p>Grunt</p>
</body>

...the structure would be:

  1. Foo (heading of explicit body section, containing the "Grunt" paragraph)
    1. Bar (heading starting implied section, containing a block quote and the "Baz" paragraph)
    2. Quux (heading starting implied section)
    3. Thud (heading of explicit section section)

Notice how the section ends the earlier implicit section so that a later paragraph ("Grunt") is back at the top level.

Sections may contain headings of any rank, but authors are strongly encouraged to either use only h1 elements, or to use elements of the appropriate rank for the section's nesting level.

Authors are also encouraged to explicitly wrap sections in elements of sectioning content, instead of relying on the implicit sections generated by having multiple headings in one element of sectioning content.

For example, the following is correct:

<body>
 <h4>Apples</h4>
 <p>Apples are fruit.</p>
 <section>
  <h2>Taste</h2>
  <p>They taste lovely.</p>
  <h6>Sweet</h6>
  <p>Red apples are sweeter than green ones.</p>
  <h1>Color</h1>
  <p>Apples come in various colors.</p>
 </section>
</body>

However, the same document would be more clearly expressed as:

<body>
 <h1>Apples</h1>
 <p>Apples are fruit.</p>
 <section>
  <h2>Taste</h2>
  <p>They taste lovely.</p>
  <section>
   <h3>Sweet</h3>
   <p>Red apples are sweeter than green ones.</p>
  </section>
 </section>
 <section>
  <h2>Color</h2>
  <p>Apples come in various colors.</p>
 </section>
</body>

Both of the documents above are semantically identical and would produce the same outline in compliant user agents.

3.4.11.1 Creating an outline

Status: Last call for comments

This section defines an algorithm for creating an outline for a sectioning content element or a sectioning root element. It is defined in terms of a walk over the nodes of a DOM tree, in tree order, with each node being visited when it is entered and when it is exited during the walk.

The outline for a sectioning content element or a sectioning root element consists of a list of one or more potentially nested sections. A section is a container that corresponds to some nodes in the original DOM tree. Each section can have one heading associated with it, and can contain any number of further nested sections. The algorithm for the outline also associates each node in the DOM tree with a particular section and potentially a heading. (The sections in the outline aren't section elements, though some may correspond to such elements — they are merely conceptual sections.)

The following markup fragment:

<body>
 <h1>A</h1>
 <p>B</p>
 <h2>C</h2>
 <p>D</p>
 <h2>E</h2>
 <p>F</p>
</body>

...results in the following outline being created for the body node (and thus the entire document):

  1. Section created for body node.

    Associated with heading "A".

    Also associated with paragraph "B".

    Nested sections:

    1. Section implied for first h2 element.

      Associated with heading "C".

      Also associated with paragraph "D".

      No nested sections.

    2. Section implied for second h2 element.

      Associated with heading "E".

      Also associated with paragraph "F".

      No nested sections.

The algorithm that must be followed during a walk of a DOM subtree rooted at a sectioning content element or a sectioning root element to determine that element's outline is as follows:

  1. Let current outlinee be null. (It holds the element whose outline is being created.)

  2. Let current section be null. (It holds a pointer to a section, so that elements in the DOM can all be associated with a section.)

  3. Create a stack to hold elements, which is used to handle nesting. Initialize this stack to empty.

  4. As you walk over the DOM in tree order, trigger the first relevant step below for each element as you enter and exit it.

    If the top of the stack is an element, and you are exiting that element

    The element being exited is a heading content element.

    Pop that element from the stack.

    If the top of the stack is a heading content element

    Do nothing.

    When entering a sectioning content element or a sectioning root element

    If current outlinee is not null, and the current section has no heading, create an implied heading and let that be the heading for the current section.

    If current outlinee is not null, push current outlinee onto the stack.

    Let current outlinee be the element that is being entered.

    Let current section be a newly created section for the current outlinee element.

    Let there be a new outline for the new current outlinee, initialized with just the new current section as the only section in the outline.

    When exiting a sectioning content element, if the stack is not empty

    Pop the top element from the stack, and let the current outlinee be that element.

    Let current section be the last section in the outline of the current outlinee element.

    Append the outline of the sectioning content element being exited to the current section. (This does not change which section is the last section in the outline.)

    When exiting a sectioning root element, if the stack is not empty

    Run these steps:

    1. Pop the top element from the stack, and let the current outlinee be that element.

    2. Let current section be the last section in the outline of the current outlinee element.

    3. Finding the deepest child: If current section has no child sections, stop these steps.

    4. Let current section be the last child section of the current current section.

    5. Go back to the substep labeled finding the deepest child.

    When exiting a sectioning content element or a sectioning root element

    The current outlinee is the element being exited.

    Let current section be the first section in the outline of the current outlinee element.

    Skip to the next step in the overall set of steps. (The walk is over.)

    If the current outlinee is null.

    Do nothing.

    When entering a heading content element

    If the current section has no heading, let the element being entered be the heading for the current section.

    Otherwise, if the element being entered has a rank equal to or greater than the heading of the last section of the outline of the current outlinee, then create a new section and append it to the outline of the current outlinee element, so that this new section is the new last section of that outline. Let current section be that new section. Let the element being entered be the new heading for the current section.

    Otherwise, run these substeps:

    1. Let candidate section be current section.

    2. If the element being entered has a rank lower than the rank of the heading of the candidate section, then create a new section, and append it to candidate section. (This does not change which section is the last section in the outline.) Let current section be this new section. Let the element being entered be the new heading for the current section. Abort these substeps.

    3. Let new candidate section be the section that contains candidate section in the outline of current outlinee.

    4. Let candidate section be new candidate section.

    5. Return to step 2.

    Push the element being entered onto the stack. (This causes the algorithm to skip any descendants of the element.)

    Recall that h1 has the highest rank, and h6 has the lowest rank.

    Otherwise

    Do nothing.

    In addition, whenever you exit a node, after doing the steps above, if current section is not null, associate the node with the section current section.

  5. If the current outlinee is null, then there was no sectioning content element or sectioning root element in the DOM. There is no outline. Abort these steps.

  6. Associate any nodes that were not associated with a section in the steps above with current outlinee as their section.

  7. Associate all nodes with the heading of the section with which they are associated, if any.

  8. If current outlinee is the body element, then the outline created for that element is the outline of the entire document.

The tree of sections created by the algorithm above, or a proper subset thereof, must be used when generating document outlines, for example when generating tables of contents.

When creating an interactive table of contents, entries should jump the user to the relevant sectioning content element, if the section was created for a real element in the original document, or to the relevant heading content element, if the section in the tree was generated for a heading in the above process.

Selecting the first section of the document therefore always takes the user to the top of the document, regardless of where the first heading in the body is to be found.

The outline depth of a heading content element associated with a section section is the number of sections that are ancestors of section in the outline that section finds itself in when the outlines of its Document's elements are created, plus 1. The outline depth of a heading content element not associated with a section is 1.

User agents should provide default headings for sections that do not have explicit section headings.

Consider the following snippet:

<body>
 <nav>
  <p><a href="/">Home</a></p>
 </nav>
 <p>Hello world.</p>
 <aside>
  <p>My cat is cute.</p>
 </aside>
</body>

Although it contains no headings, this snippet has three sections: a document (the body) with two subsections (a nav and an aside). A user agent could present the outline as follows:

  1. Untitled document
    1. Navigation
    2. Sidebar

These default headings ("Untitled document", "Navigation", "Sidebar") are not specified by this specification, and might vary with the user's language, the page's language, the user's preferences, the user agent implementor's preferences, etc.

The following JavaScript function shows how the tree walk could be implemented. The root argument is the root of the tree to walk, and the enter and exit arguments are callbacks that are called with the nodes as they are entered and exited. [ECMA262]

function (root, enter, exit) {
  var node = root;
  start: while (node) {
    enter(node);
    if (node.firstChild) {
      node = node.firstChild;
      continue start;
    }
    while (node) {
      exit(node);
      if (node.nextSibling) {
        node = node.nextSibling;
        continue start;
      }
      if (node == root)
        node = null;
      else
        node = node.parentNode;
    }
  }
}

3.5 Grouping content

Status: Last call for comments

3.5.1 The p element

Status: Last call for comments

Categories
Flow content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
interface HTMLParagraphElement : HTMLElement {};

The p element represents a paragraph.

The following examples are conforming HTML fragments:

<p>The little kitten gently seated himself on a piece of
carpet. Later in his life, this would be referred to as the time the
cat sat on the mat.</p>
<fieldset>
 <legend>Personal information</legend>
 <p>
   <label>Name: <input name="n"></label>
   <label><input name="anon" type="checkbox"> Hide from other users</label>
 </p>
 <p><label>Address: <textarea name="a"></textarea></label></p>
</fieldset>
<p>There was once an example from Femley,<br>
Whose markup was of dubious quality.<br>
The validator complained,<br>
So the author was pained,<br>
To move the error from the markup to the rhyming.</p>

The p element should not be used when a more specific element is more appropriate.

The following example is technically correct:

<section>
 <!-- ... -->
 <p>Last modified: 2001-04-23</p>
 <p>Author: fred@example.com</p>
</section>

However, it would be better marked-up as:

<section>
 <!-- ... -->
 <footer>Last modified: 2001-04-23</footer>
 <address>Author: fred@example.com</address>
</section>

Or:

<section>
 <!-- ... -->
 <footer>
  <p>Last modified: 2001-04-23</p>
  <address>Author: fred@example.com</address>
 </footer>
</section>

3.5.2 The hr element

Status: Last call for comments

Categories
Flow content.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Empty.
Content attributes:
Global attributes
DOM interface:
interface HTMLHRElement : HTMLElement {};

The hr element represents a paragraph-level thematic break, e.g. a scene change in a story, or a transition to another topic within a section of a reference book.

The following extract from Pandora's Star by Peter F. Hamilton shows two paragraphs that precede a scene change and the paragraph that follows it. The scene change, represented in the printed book by a gap containing a solitary centered star between the second and third paragraphs, is here represented using the hr element.

<p>Dudley was ninety-two, in his second life, and fast approaching
time for another rejuvenation. Despite his body having the physical
age of a standard fifty-year-old, the prospect of a long degrading
campaign within academia was one he regarded with dread. For a
supposedly advanced civilization, the Intersolar Commonwearth could be
appallingly backward at times, not to mention cruel.</p>
<p><i>Maybe it won't be that bad</i>, he told himself. The lie was
comforting enough to get him through the rest of the night's
shift.</p>
<hr>
<p>The Carlton AllLander drove Dudley home just after dawn. Like the
astronomer, the vehicle was old and worn, but perfectly capable of
doing its job. It had a cheap diesel engine, common enough on a
semi-frontier world like Gralmond, although its drive array was a
thoroughly modern photoneural processor. With its high suspension and
deep-tread tyres it could plough along the dirt track to the
observatory in all weather and seasons, including the metre-deep snow
of Gralmond's winters.</p>

3.5.3 The br element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Empty.
Content attributes:
Global attributes
DOM interface:
interface HTMLBRElement : HTMLElement {};

The br element represents a line break.

br elements must be used only for line breaks that are actually part of the content, as in poems or addresses.

The following example is correct usage of the br element:

<p>P. Sherman<br>
42 Wallaby Way<br>
Sydney</p>

br elements must not be used for separating thematic groups in a paragraph.

The following examples are non-conforming, as they abuse the br element:

<p><a ...>34 comments.</a><br>
<a ...>Add a comment.</a></p>
<p><label>Name: <input name="name"></label><br>
<label>Address: <input name="address"></label></p>

Here are alternatives to the above, which are correct:

<p><a ...>34 comments.</a></p>
<p><a ...>Add a comment.</a></p>
<p><label>Name: <input name="name"></label></p>
<p><label>Address: <input name="address"></label></p>

If a paragraph consists of nothing but a single br element, it represents a placeholder blank line (e.g. as in a template). Such blank lines must not be used for presentation purposes.

Any content inside br elements must not be considered part of the surrounding text.

A br element does not separate paragraphs for the purposes of the Unicode bidirectional algorithm. [BIDI]

3.5.4 The pre element

Status: Last call for comments

Categories
Flow content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
interface HTMLPreElement : HTMLElement {};

The pre element represents a block of preformatted text, in which structure is represented by typographic conventions rather than by elements.

In the HTML syntax, a leading newline character immediately following the pre element start tag is stripped.

Some examples of cases where the pre element could be used:

Authors are encouraged to consider how preformatted text will be experienced when the formatting is lost, as will be the case for users of speech synthesizers, braille displays, and the like. For cases like ASCII art, it is likely that an alternative presentation, such as a textual description, would be more universally accessible to the readers of the document.

To represent a block of computer code, the pre element can be used with a code element; to represent a block of computer output the pre element can be used with a samp element. Similarly, the kbd element can be used within a pre element to indicate text that the user is to enter.

In the following snippet, a sample of computer code is presented.

<p>This is the <code>Panel</code> constructor:</p>
<pre><code>function Panel(element, canClose, closeHandler) {
  this.element = element;
  this.canClose = canClose;
  this.closeHandler = function () { if (closeHandler) closeHandler() };
}</code></pre>

In the following snippet, samp and kbd elements are mixed in the contents of a pre element to show a session of Zork I.

<pre><samp>You are in an open field west of a big white house with a boarded
front door.
There is a small mailbox here.

></samp> <kbd>open mailbox</kbd>

<samp>Opening the mailbox reveals:
A leaflet.

></samp></pre>

The following shows a contemporary poem that uses the pre element to preserve its unusual formatting, which forms an intrinsic part of the poem itself.

<pre>                maxling

it is with a          heart
               heavy

that i admit loss of a feline
        so           loved

a friend lost to the
        unknown
                                (night)

~cdr 11dec07</pre>

3.5.5 The blockquote element

Status: Last call for comments

Categories
Flow content.
Sectioning root.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content.
Content attributes:
Global attributes
cite
DOM interface:
interface HTMLQuoteElement : HTMLElement {
           attribute DOMString cite;
};

The HTMLQuoteElement interface is also used by the q element.

The blockquote element represents a section that is quoted from another source.

Content inside a blockquote must be quoted from another source, whose address, if it has one, should be cited in the cite attribute.

If the cite attribute is present, it must be a valid URL. To obtain the corresponding citation link, the value of the attribute must be resolved relative to the element. User agents should allow users to follow such citation links.

The cite IDL attribute must reflect the element's cite content attribute.

This next example shows the use of cite alongside blockquote:

<p>His next piece was the aptly named <cite>Sonnet 130</cite>:</p>
<blockquote cite="http://quotes.example.org/s/sonnet130.html">
  <p>My mistress' eyes are nothing like the sun,<br>
  Coral is far more red, than her lips red,<br>
  ...

This example shows how a forum post could use blockquote to show what post a user is replying to. The article element is used for each post, to mark up the threading.

<article>
 <h1><a href="http://bacon.example.com/?blog=109431">Bacon on a crowbar</a></h1>
 <article>
  <header><strong>t3yw</strong> 12 points 1 hour ago</header>
  <p>I bet a narwhal would love that.</p>
  <footer><a href="?pid=29578">permalink</a></footer>
  <article>
   <header><strong>greg</strong> 8 points 1 hour ago</header>
   <blockquote><p>I bet a narwhal would love that.</p></blockquote>
   <p>Dude narwhals don't eat bacon.</p>
   <footer><a href="?pid=29579">permalink</a></footer>
   <article>
    <header><strong>t3yw</strong> 15 points 1 hour ago</header>
    <blockquote>
     <blockquote><p>I bet a narwhal would love that.</p></blockquote>
     <p>Dude narwhals don't eat bacon.</p>
    </blockquote>
    <p>Next thing you'll be saying they don't get capes and wizard
    hats either!</p>
    <footer><a href="?pid=29580">permalink</a></footer>
    <article>
     <article>
      <header><strong>boing</strong> -5 points 1 hour ago</header>
      <p>narwhals are worse than ceiling cat</p>
      <footer><a href="?pid=29581">permalink</a></footer>
     </article>
    </article>
   </article>
  </article>
  <article>
   <header><strong>fred</strong> 1 points 23 minutes ago</header>
   <blockquote><p>I bet a narwhal would love that.</p></blockquote>
   <p>I bet they'd love to peel a banana too.</p>
   <footer><a href="?pid=29582">permalink</a></footer>
  </article>
 </article>
</article>

Examples of how to represent a conversation are shown in a later section; it is not appropriate to use the cite and blockquote elements for this purpose.

3.5.6 The ol element

Status: Last call for comments

Categories
Flow content.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Zero or more li elements.
Content attributes:
Global attributes
reversed
start
DOM interface:
interface HTMLOListElement : HTMLElement {
           attribute boolean reversed;
           attribute long start;
};

The ol element represents a list of items, where the items have been intentionally ordered, such that changing the order would change the meaning of the document.

The items of the list are the li element child nodes of the ol element, in tree order.

The reversed attribute is a boolean attribute. If present, it indicates that the list is a descending list (..., 3, 2, 1). If the attribute is omitted, the list is an ascending list (1, 2, 3, ...).

The start attribute, if present, must be a valid integer giving the ordinal value of the first list item.

If the start attribute is present, user agents must parse it as an integer, in order to determine the attribute's value. The default value, used if the attribute is missing or if the value cannot be converted to a number according to the referenced algorithm, is 1 if the element has no reversed attribute, and is the number of child li elements otherwise.

The first item in the list has the ordinal value given by the ol element's start attribute, unless that li element has a value attribute with a value that can be successfully parsed, in which case it has the ordinal value given by that value attribute.

Each subsequent item in the list has the ordinal value given by its value attribute, if it has one, or, if it doesn't, the ordinal value of the previous item, plus one if the reversed is absent, or minus one if it is present.

The reversed IDL attribute must reflect the value of the reversed content attribute.

The start IDL attribute must reflect the value of the start content attribute.

The following markup shows a list where the order matters, and where the ol element is therefore appropriate. Compare this list to the equivalent list in the ul section to see an example of the same items using the ul element.

<p>I have lived in the following countries (given in the order of when
I first lived there):</p>
<ol>
 <li>Switzerland
 <li>United Kingdom
 <li>United States
 <li>Norway
</ol>

Note how changing the order of the list changes the meaning of the document. In the following example, changing the relative order of the first two items has changed the birthplace of the author:

<p>I have lived in the following countries (given in the order of when
I first lived there):</p>
<ol>
 <li>United Kingdom
 <li>Switzerland
 <li>United States
 <li>Norway
</ol>

3.5.7 The ul element

Status: Last call for comments

Categories
Flow content.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Zero or more li elements.
Content attributes:
Global attributes
DOM interface:
interface HTMLUListElement : HTMLElement {};

The ul element represents a list of items, where the order of the items is not important — that is, where changing the order would not materially change the meaning of the document.

The items of the list are the li element child nodes of the ul element.

The following markup shows a list where the order does not matter, and where the ul element is therefore appropriate. Compare this list to the equivalent list in the ol section to see an example of the same items using the ol element.

<p>I have lived in the following countries:</p>
<ul>
 <li>Norway
 <li>Switzerland
 <li>United Kingdom
 <li>United States
</ul>

Note that changing the order of the list does not change the meaning of the document. The items in the snippet above are given in alphabetical order, but in the snippet below they are given in order of the size of their current account balance in 2007, without changing the meaning of the document whatsoever:

<p>I have lived in the following countries:</p>
<ul>
 <li>Switzerland
 <li>Norway
 <li>United Kingdom
 <li>United States
</ul>

3.5.8 The li element

Status: Last call for comments

Categories
None.
Contexts in which this element may be used:
Inside ol elements.
Inside ul elements.
Inside menu elements.
Content model:
Flow content.
Content attributes:
Global attributes
If the element is a child of an ol element: value
DOM interface:
interface HTMLLIElement : HTMLElement {
           attribute long value;
};

The li element represents a list item. If its parent element is an ol, ul, or menu element, then the element is an item of the parent element's list, as defined for those elements. Otherwise, the list item has no defined list-related relationship to any other li element.

The value attribute, if present, must be a valid integer giving the ordinal value of the list item.

If the value attribute is present, user agents must parse it as an integer, in order to determine the attribute's value. If the attribute's value cannot be converted to a number, the attribute must be treated as if it was absent. The attribute has no default value.

The value attribute is processed relative to the element's parent ol element (q.v.), if there is one. If there is not, the attribute has no effect.

The value IDL attribute must reflect the value of the value content attribute.

The following example, the top ten movies are listed (in reverse order). Note the way the list is given a title by using a figure element and its dt element.

<figure>
 <dt>The top 10 movies of all time</dt>
 <dd>
  <ol>
   <li value="10"><cite>Josie and the Pussycats</cite>, 2001</li>
   <li value="9"><cite lang="sh">Црна мачка, бели мачор</cite>, 1998</li>
   <li value="8"><cite>A Bug's Life</cite>, 1998</li>
   <li value="7"><cite>Toy Story</cite>, 1995</li>
   <li value="6"><cite>Monsters, Inc</cite>, 2001</li>
   <li value="5"><cite>Cars</cite>, 2006</li>
   <li value="4"><cite>Toy Story 2</cite>, 1999</li>
   <li value="3"><cite>Finding Nemo</cite>, 2003</li>
   <li value="2"><cite>The Incredibles</cite>, 2004</li>
   <li value="1"><cite>Ratatouille</cite>, 2007</li>
  </ol>
 <dd>
</figure>

The markup could also be written as follows, using the reversed attribute on the ol element:

<figure>
 <dt>The top 10 movies of all time</dt>
 <dd>
  <ol reversed>
   <li><cite>Josie and the Pussycats</cite>, 2001</li>
   <li><cite lang="sh">Црна мачка, бели мачор</cite>, 1998</li>
   <li><cite>A Bug's Life</cite>, 1998</li>
   <li><cite>Toy Story</cite>, 1995</li>
   <li><cite>Monsters, Inc</cite>, 2001</li>
   <li><cite>Cars</cite>, 2006</li>
   <li><cite>Toy Story 2</cite>, 1999</li>
   <li><cite>Finding Nemo</cite>, 2003</li>
   <li><cite>The Incredibles</cite>, 2004</li>
   <li><cite>Ratatouille</cite>, 2007</li>
  </ol>
 </dd>
</figure>

If the li element is the child of a menu element and itself has a child that defines a command, then the li element will match the :enabled and :disabled pseudo-classes in the same way as the first such child element does.

3.5.9 The dl element

Status: Last call for comments

Categories
Flow content.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Zero or more groups each consisting of one or more dt elements followed by one or more dd elements.
Content attributes:
Global attributes
DOM interface:
interface HTMLDListElement : HTMLElement {};

The dl element represents an association list consisting of zero or more name-value groups (a description list). Each group must consist of one or more names (dt elements) followed by one or more values (dd elements). Within a single dl element, there should not be more than one dt element for each name.

Name-value groups may be terms and definitions, metadata topics and values, or any other groups of name-value data.

The values within a group are alternatives; multiple paragraphs forming part of the same value must all be given within the same dd element.

The order of the list of groups, and of the names and values within each group, may be significant.

If a dl element is empty, it contains no groups.

If a dl element contains non-whitespace text nodes, or elements other than dt and dd, then those elements or text nodes do not form part of any groups in that dl.

If a dl element contains only dt elements, then it consists of one group with names but no values.

If a dl element contains only dd elements, then it consists of one group with values but no names.

If a dl element starts with one or more dd elements, then the first group has no associated name.

If a dl element ends with one or more dt elements, then the last group has no associated value.

When a dl element doesn't match its content model, it is often due to accidentally using dd elements in the place of dt elements and vice versa. Conformance checkers can spot such mistakes and might be able to advise authors how to correctly use the markup.

In the following example, one entry ("Authors") is linked to two values ("John" and "Luke").

<dl>
 <dt> Authors
 <dd> John
 <dd> Luke
 <dt> Editor
 <dd> Frank
</dl>

In the following example, one definition is linked to two terms.

<dl>
 <dt lang="en-US"> <dfn>color</dfn> </dt>
 <dt lang="en-GB"> <dfn>colour</dfn> </dt>
 <dd> A sensation which (in humans) derives from the ability of
 the fine structure of the eye to distinguish three differently
 filtered analyses of a view. </dd>
</dl>

The following example illustrates the use of the dl element to mark up metadata of sorts. At the end of the example, one group has two metadata labels ("Authors" and "Editors") and two values ("Robert Rothman" and "Daniel Jackson").

<dl>
 <dt> Last modified time </dt>
 <dd> 2004-12-23T23:33Z </dd>
 <dt> Recommended update interval </dt>
 <dd> 60s </dd>
 <dt> Authors </dt>
 <dt> Editors </dt>
 <dd> Robert Rothman </dd>
 <dd> Daniel Jackson </dd>
</dl>

The following example shows the dl element used to give a set of instructions. The order of the instructions here is important (in the other examples, the order of the blocks was not important).

<p>Determine the victory points as follows (use the
first matching case):</p>
<dl>
 <dt> If you have exactly five gold coins </dt>
 <dd> You get five victory points </dd>
 <dt> If you have one or more gold coins, and you have one or more silver coins </dt>
 <dd> You get two victory points </dd>
 <dt> If you have one or more silver coins </dt>
 <dd> You get one victory point </dd>
 <dt> Otherwise </dt>
 <dd> You get no victory points </dd>
</dl>

The following snippet shows a dl element being used as a glossary. Note the use of dfn to indicate the word being defined.

<dl>
 <dt><dfn>Apartment</dfn>, n.</dt>
 <dd>An execution context grouping one or more threads with one or
 more COM objects.</dd>
 <dt><dfn>Flat</dfn>, n.</dt>
 <dd>A deflated tire.</dd>
 <dt><dfn>Home</dfn>, n.</dt>
 <dd>The user's login directory.</dd>
</dl>

The dl element is inappropriate for marking up dialogue. Examples of how to mark up dialogue are shown below.

3.5.10 The dt element

Status: Last call for comments

Categories
None.
Contexts in which this element may be used:
Before dd or dt elements inside dl elements.
In a figure element containing no other dt element children.
As the first child of a details element.
Content model:
When the parent node is a figure element: flow content, but with no descendant figure elements.
Otherwise: phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The dt element represents either: the term, or name, part of a term-description group in a description list (dl element); or, the caption of a figure element; or, the summary of a details element.

The dt element itself, when used in a dl element, does not indicate that its contents are a term being defined, but this can be indicated using the dfn element.

3.5.11 The dd element

Status: Last call for comments

Categories
None.
Contexts in which this element may be used:
After dt or dd elements inside dl elements.
In a figure element containing no other dd element children.
As the last child of a details element.
Content model:
Flow content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The dd element represents either: the description, definition, or value, part of a term-description group in a description list (dl element); or, the data of a figure element; or, the details of a details element.

A dl can be used to define a vocabulary list, like in a dictionary. In the following example, each entry, given by a dt with a dfn, has several dds, showing the various parts of the definition.

<dl>
 <dt><dfn>happiness</dfn></dt>
 <dd class="pronunciation">/'hæ p. nes/</dd>
 <dd class="part-of-speech"><i><abbr>n.</abbr></i></dd>
 <dd>The state of being happy.</dd>
 <dd>Good fortune; success. <q>Oh <b>happiness</b>! It worked!</q></dd>
 <dt><dfn>rejoice</dfn></dt>
 <dd class="pronunciation">/ri jois'/</dd>
 <dd><i class="part-of-speech"><abbr>v.intr.</abbr></i> To be delighted oneself.</dd>
 <dd><i class="part-of-speech"><abbr>v.tr.</abbr></i> To cause one to be delighted.</dd>
</dl>

3.5.12 The div element

Status: Last call for comments

Categories
Flow content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content.
Content attributes:
Global attributes
DOM interface:
interface HTMLDivElement : HTMLElement {};

The div element has no special meaning at all. It represents its children. It can be used with the class, lang, and title attributes to mark up semantics common to a group of consecutive elements.

Authors are strongly encouraged to view the div element as an element of last resort, for when no other element is suitable. Use of the div element instead of more appropriate elements leads to poor accessibility for readers and poor maintainability for authors.

For example, a blog post would be marked up using article, a chapter using section, a page's navigation aids using nav, and a group of form controls using fieldset.

On the other hand, div elements can be useful for stylistic purposes or to wrap multiple paragraphs within a section that are all to be annotated in a similar way. In the following example, we see div elements used as a way to set the language of two paragraphs at once, instead of setting the language on the two paragraph elements separately:

<article lang="en-US">
 <h1>My use of language and my cats</h1>
 <p>My cat's behavior hasn't changed much since her absence, except
 that she plays her new physique to the neighbors regularly, in an
 attempt to get pets.</p>
 <div lang="en-GB">
  <p>My other cat, coloured black and white, is a sweetie. He followed
  us to the pool today, walking down the pavement with us. Yesterday
  he apparently visited our neighbours. I wonder if he recognises that
  their flat is a mirror image of ours.</p>
  <p>Hm, I just noticed that in the last paragraph I used British
  English. But I'm supposed to write in American English. So I
  shouldn't say "pavement" or "flat" or "colour"...</p>
 </div>
 <p>I should say "sidewalk" and "apartment" and "color"!</p>
</article>

3.6 Text-level semantics

Status: Last call for comments

3.6.1 The a element

Status: Last call for comments

Categories
Flow content.
When the element only contains phrasing content: phrasing content.
Interactive content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Transparent, but there must be no interactive content descendant.
Content attributes:
Global attributes
href
target
ping
rel
media
hreflang
type
DOM interface:
interface HTMLAnchorElement : HTMLElement {
  stringifier attribute DOMString href;
           attribute DOMString target;
           attribute DOMString ping;
           attribute DOMString rel;
  readonly attribute DOMTokenList relList;
           attribute DOMString media;
           attribute DOMString hreflang;
           attribute DOMString type;

  // URL decomposition IDL attributes
           attribute DOMString protocol;
           attribute DOMString host;
           attribute DOMString hostname;
           attribute DOMString port;
           attribute DOMString pathname;
           attribute DOMString search;
           attribute DOMString hash;
};

If the a element has an href attribute, then it represents a hyperlink (a hypertext anchor).

If the a element has no href attribute, then the element represents a placeholder for where a link might otherwise have been placed, if it had been relevant.

The target, ping, rel, media, hreflang, and type attributes must be omitted if the href attribute is not present.

If a site uses a consistent navigation toolbar on every page, then the link that would normally link to the page itself could be marked up using an a element:

<nav>
 <ul>
  <li> <a href="/">Home</a> </li>
  <li> <a href="/news">News</a> </li>
  <li> <a>Examples</a> </li>
  <li> <a href="/legal">Legal</a> </li>
 </ul>
</nav>

The href, target and ping attributes affect what happens when users follow hyperlinks created using the a element. The rel, media, hreflang, and type attributes may be used to indicate to the user the likely nature of the target resource before the user follows the link.

The activation behavior of a elements that represent hyperlinks is to run the following steps:

  1. If the DOMActivate event in question is not trusted (i.e. a click() method call was the reason for the event being dispatched), and the a element's target attribute is such that applying the rules for choosing a browsing context given a browsing context name, using the value of the target attribute as the browsing context name, would result in there not being a chosen browsing context, then raise an INVALID_ACCESS_ERR exception and abort these steps.

  2. If the target of the click event is an img element with an ismap attribute specified, then server-side image map processing must be performed, as follows:

    1. If the DOMActivate event was dispatched as the result of a real pointing-device-triggered click event on the img element, then let x be the distance in CSS pixels from the left edge of the image's left border, if it has one, or the left edge of the image otherwise, to the location of the click, and let y be the distance in CSS pixels from the top edge of the image's top border, if it has one, or the top edge of the image otherwise, to the location of the click. Otherwise, let x and y be zero.
    2. Let the hyperlink suffix be a U+003F QUESTION MARK character, the value of x expressed as a base-ten integer using ASCII digits, a U+002C COMMA character (,), and the value of y expressed as a base-ten integer using ASCII digits. ASCII digits are the characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9).
  3. Finally, the user agent must follow the hyperlink defined by the a element. If the steps above defined a hyperlink suffix, then take that into account when following the hyperlink.

The IDL attributes href, ping, target, rel, media, hreflang, and type, must reflect the respective content attributes of the same name.

The IDL attribute relList must reflect the rel content attribute.

The a element also supports the complement of URL decomposition IDL attributes, protocol, host, port, hostname, pathname, search, and hash. These must follow the rules given for URL decomposition IDL attributes, with the input being the result of resolving the element's href attribute relative to the element, if there is such an attribute and resolving it is successful, or the empty string otherwise; and the common setter action being the same as setting the element's href attribute to the new output value.

The a element may be wrapped around entire paragraphs, lists, tables, and so forth, even entire sections, so long as there is no interactive content within (e.g. buttons or other links). This example shows how this can be used to make an entire advertising block into a link:

<aside class="advertising">
 <h1>Advertising</h1>
 <a href="http://ad.example.com/?adid=1929&amp;pubid=1422">
  <section>
   <h1>Mellblomatic 9000!</h1>
   <p>Turn all your widgets into mellbloms!</p>
   <p>Only $9.99 plus shipping and handling.</p>
  </section>
 </a>
 <a href="http://ad.example.com/?adid=375&amp;pubid=1422">
  <section>
   <h1>The Mellblom Browser</h1>
   <p>Web browsing at the speed of light.</p>
   <p>No other browser goes faster!</p>
  </section>
 </a>
</aside>

3.6.2 The em element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The em element represents stress emphasis of its contents.

The level of emphasis that a particular piece of content has is given by its number of ancestor em elements.

The placement of emphasis changes the meaning of the sentence. The element thus forms an integral part of the content. The precise way in which emphasis is used in this way depends on the language.

These examples show how changing the emphasis changes the meaning. First, a general statement of fact, with no emphasis:

<p>Cats are cute animals.</p>

By emphasizing the first word, the statement implies that the kind of animal under discussion is in question (maybe someone is asserting that dogs are cute):

<p><em>Cats</em> are cute animals.</p>

Moving the emphasis to the verb, one highlights that the truth of the entire sentence is in question (maybe someone is saying cats are not cute):

<p>Cats <em>are</em> cute animals.</p>

By moving it to the adjective, the exact nature of the cats is reasserted (maybe someone suggested cats were mean animals):

<p>Cats are <em>cute</em> animals.</p>

Similarly, if someone asserted that cats were vegetables, someone correcting this might emphasize the last word:

<p>Cats are cute <em>animals</em>.</p>

By emphasizing the entire sentence, it becomes clear that the speaker is fighting hard to get the point across. This kind of emphasis also typically affects the punctuation, hence the exclamation mark here.

<p><em>Cats are cute animals!</em></p>

Anger mixed with emphasizing the cuteness could lead to markup such as:

<p><em>Cats are <em>cute</em> animals!</em></p>

The em element isn't a generic "italics" element. Sometimes, text is intended to stand out from the rest of the paragraph, as if it was in a different mood or voice. For this, the i element is more appropriate.

The em element also isn't intended to convey importance; for that purpose, the strong element is more appropriate.

3.6.3 The strong element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The strong element represents strong importance for its contents.

The relative level of importance of a piece of content is given by its number of ancestor strong elements; each strong element increases the importance of its contents.

Changing the importance of a piece of text with the strong element does not change the meaning of the sentence.

Here is an example of a warning notice in a game, with the various parts marked up according to how important they are:

<p><strong>Warning.</strong> This dungeon is dangerous.
<strong>Avoid the ducks.</strong> Take any gold you find.
<strong><strong>Do not take any of the diamonds</strong>,
they are explosive and <strong>will destroy anything within
ten meters.</strong></strong> You have been warned.</p>

3.6.4 The small element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The small element represents side comments such as small print.

Small print typically features disclaimers, caveats, legal restrictions, or copyrights. Small print is also sometimes used for attribution, or for satisfying licensing requirements.

The small element does not "de-emphasize" or lower the importance of text emphasized by the em element or marked as important with the strong element.

The small element should not be used for extended spans of text, such as multiple paragraphs, lists, or sections of text. It is only intended for short runs of text. The text of a page listing terms of use, for instance, would not be a suitable candidate for the small element: in such a case, the text is not a side comment, it is the main content of the page.

In this example the footer contains contact information and a copyright notice.

<footer>
 <address>
  For more details, contact
  <a href="mailto:js@example.com">John Smith</a>.
 </address>
 <p><small>© copyright 2038 Example Corp.</small></p>
</footer>

In this second example, the small element is used for a side comment in an article.

<p>Example Corp today announced record profits for the
second quarter <small>(Full Disclosure: Foo News is a subsidiary of
Example Corp)</small>, leading to speculation about a third quarter
merger with Demo Group.</p>

This is distinct from a sidebar, which might be multiple paragraphs long and is removed from the main flow of text. In the following example, we see a sidebar from the same article. This sidebar also has small print, indicating the source of the information in the sidebar.

<aside>
 <h1>Example Corp</h1>
 <p>This company mostly creates small software and Web
 sites.</p>
 <p>The Example Corp company mission is "To provide entertainment
 and news on a sample basis".</p>
 <p><small>Information obtained from <a
 href="http://example.com/about.html">example.com</a> home
 page.</small></p>
</aside>

In this last example, the small element is marked as being important small print.

<p><strong><small>Continued use of this service will result in a kiss.</small></strong></p>

3.6.5 The cite element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The cite element represents the title of a work (e.g. a book, a paper, an essay, a poem, a score, a song, a script, a film, a TV show, a game, a sculpture, a painting, a theatre production, a play, an opera, a musical, an exhibition, a legal case report, etc). This can be a work that is being quoted or referenced in detail (i.e. a citation), or it can just be a work that is mentioned in passing.

A person's name is not the title of a work — even if people call that person a piece of work — and the element must therefore not be used to mark up people's names. (In some cases, the b element might be appropriate for names; e.g. in a gossip article where the names of famous people are keywords rendered with a different style to draw attention to them. In other cases, if an element is really needed, the span element can be used.)

This next example shows a typical use of the cite element:

<p>My favorite book is <cite>The Reality Dysfunction</cite> by
Peter F. Hamilton. My favorite comic is <cite>Pearls Before
Swine</cite> by Stephan Pastis. My favorite track is <cite>Jive
Samba</cite> by the Cannonball Adderley Sextet.</p>

This is correct usage:

<p>According to the Wikipedia article <cite>HTML</cite>, as it
stood in mid-February 2008, leaving attribute values unquoted is
unsafe. This is obviously an over-simplification.</p>

The following, however, is incorrect usage, as the cite element here is containing far more than the title of the work:

<!-- do not copy this example, it is an example of bad usage! -->
<p>According to <cite>the Wikipedia article on HTML</cite>, as it
stood in mid-February 2008, leaving attribute values unquoted is
unsafe. This is obviously an over-simplification.</p>

The cite element is obviously a key part of any citation in a bibliography, but it is only used to mark the title:

<p><cite>Universal Declaration of Human Rights</cite>, United Nations,
December 1948. Adopted by General Assembly resolution 217 A (III).</p>

A citation is not a quote (for which the q element is appropriate).

This is incorrect usage, because cite is not for quotes:

<p><cite>This is wrong!</cite>, said Ian.</p>

This is also incorrect usage, because a person is not a work:

<p><q>This is still wrong!</q>, said <cite>Ian</cite>.</p>

The correct usage does not use a cite element:

<p><q>This is correct</q>, said Ian.</p>

As mentioned above, the b element might be relevant for marking names as being keywords in certain kinds of documents:

<p>And then <b>Ian</b> said <q>this might be right, in a
gossip column, maybe!</q>.</p>

3.6.6 The q element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
cite
DOM interface:
Uses HTMLQuoteElement.

The q element represents some phrasing content quoted from another source.

Quotation punctuation (such as quotation marks) that is quoting the contents of the element must not appear immediately before, after, or inside q elements; they will be inserted into the rendering by the user agent.

Content inside a q element must be quoted from another source, whose address, if it has one, should be cited in the cite attribute. The source may be fictional, as when quoting characters in a novel or screenplay.

If the cite attribute is present, it must be a valid URL. To obtain the corresponding citation link, the value of the attribute must be resolved relative to the element. User agents should allow users to follow such citation links.

The q element must not be used in place of quotation marks that do not represent quotes; for example, it is inappropriate to use the q element for marking up sarcastic statements.

The use of q elements to mark up quotations is entirely optional; using explicit quotation punctuation without q elements is just as correct.

Here is a simple example of the use of the q element:

<p>The man said <q>Things that are impossible just take
longer</q>. I disagreed with him.</p>

Here is an example with both an explicit citation link in the q element, and an explicit citation outside:

<p>The W3C page <cite>About W3C</cite> says the W3C's
mission is <q cite="http://www.w3.org/Consortium/">To lead the
World Wide Web to its full potential by developing protocols and
guidelines that ensure long-term growth for the Web</q>. I
disagree with this mission.</p>

In the following example, the quotation itself contains a quotation:

<p>In <cite>Example One</cite>, he writes <q>The man
said <q>Things that are impossible just take longer</q>. I
disagreed with him</q>. Well, I disagree even more!</p>

In the following example, quotation marks are used instead of the q element:

<p>His best argument was ❝I disagree❞, which
I thought was laughable.</p>

In the following example, there is no quote — the quotation marks are used to name a word. Use of the q element in this case would be inappropriate.

<p>The word "ineffable" could have been used to describe the disaster
resulting from the campaign's mismanagement.</p>

3.6.7 The dfn element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content, but there must be no dfn element descendants.
Content attributes:
Global attributes
Also, the title attribute has special semantics on this element.
DOM interface:
Uses HTMLElement.

The dfn element represents the defining instance of a term. The paragraph, description list group, or section that is the nearest ancestor of the dfn element must also contain the definition(s) for the term given by the dfn element.

Defining term: If the dfn element has a title attribute, then the exact value of that attribute is the term being defined. Otherwise, if it contains exactly one element child node and no child text nodes, and that child element is an abbr element with a title attribute, then the exact value of that attribute is the term being defined. Otherwise, it is the exact textContent of the dfn element that gives the term being defined.

If the title attribute of the dfn element is present, then it must contain only the term being defined.

The title attribute of ancestor elements does not affect dfn elements.

An a element that links to a dfn element represents an instance of the term defined by the dfn element.

In the following fragment, the term "GDO" is first defined in the first paragraph, then used in the second.

<p>The <dfn><abbr title="Garage Door Opener">GDO</abbr></dfn>
is a device that allows off-world teams to open the iris.</p>
<!-- ... later in the document: -->
<p>Teal'c activated his <abbr title="Garage Door Opener">GDO</abbr>
and so Hammond ordered the iris to be opened.</p>

With the addition of an a element, the reference can be made explicit:

<p>The <dfn id=gdo><abbr title="Garage Door Opener">GDO</abbr></dfn>
is a device that allows off-world teams to open the iris.</p>
<!-- ... later in the document: -->
<p>Teal'c activated his <a href=#gdo><abbr title="Garage Door Opener">GDO</abbr></a>
and so Hammond ordered the iris to be opened.</p>

3.6.8 The abbr element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
Also, the title attribute has special semantics on this element.
DOM interface:
Uses HTMLElement.

The abbr element represents an abbreviation or acronym, optionally with its expansion. The title attribute may be used to provide an expansion of the abbreviation. The attribute, if specified, must contain an expansion of the abbreviation, and nothing else.

The paragraph below contains an abbreviation marked up with the abbr element. This paragraph defines the term "Web Hypertext Application Technology Working Group".

<p>The <dfn id=whatwg><abbr
title="Web Hypertext Application Technology Working Group">WHATWG</abbr></dfn>
is a loose unofficial collaboration of Web browser manufacturers and
interested parties who wish to develop new technologies designed to
allow authors to write and deploy Applications over the World Wide
Web.</p>

An alternative way to write this would be:

<p>The <dfn id=whatwg>Web Hypertext Application Technology
Working Group</dfn> (<abbr
title="Web Hypertext Application Technology Working Group">WHATWG</abbr>)
is a loose unofficial collaboration of Web browser manufacturers and
interested parties who wish to develop new technologies designed to
allow authors to write and deploy Applications over the World Wide
Web.</p>

This paragraph has two abbreviations. Notice how only one is defined; the other, with no expansion associated with it, does not use the abbr element.

<p>The
<abbr title="Web Hypertext Application Technology Working Group">WHATWG</abbr>
started working on HTML5 in 2004.</p>

This paragraph links an abbreviation to its definition.

<p>The <a href="#whatwg"><abbr
title="Web Hypertext Application Technology Working Group">WHATWG</abbr></a>
community does not have much representation from Asia.</p>

This paragraph marks up an abbreviation without giving an expansion, possibly as a hook to apply styles for abbreviations (e.g. smallcaps).

<p>Philip` and Dashiva both denied that they were going to
get the issue counts from past revisions of the specification to
backfill the <abbr>WHATWG</abbr> issue graph.</p>

If an abbreviation is pluralized, the expansion's grammatical number (plural vs singular) must match the grammatical number of the contents of the element.

Here the plural is outside the element, so the expansion is in the singular:

<p>Two <abbr title="Working Group">WG</abbr>s worked on
this specification: the <abbr>WHATWG</abbr> and the
<abbr>HTMLWG</abbr>.</p>

Here the plural is inside the element, so the expansion is in the plural:

<p>Two <abbr title="Working Groups">WGs</abbr> worked on
this specification: the <abbr>WHATWG</abbr> and the
<abbr>HTMLWG</abbr>.</p>

Abbreviations do not have to be marked up using this element. It is expected to be useful in the following cases:

Providing an expansion in a title attribute once will not necessarily cause other abbr elements in the same document with the same contents but without a title attribute to behave as if they had the same expansion. Every abbr element is independent.

3.6.9 The time element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content, but there must be no time element descendants.
Content attributes:
Global attributes
datetime
pubdate
DOM interface:
interface HTMLTimeElement : HTMLElement {
           attribute DOMString dateTime;
           attribute boolean pubDate;
  readonly attribute Date valueAsDate;
};

The time element represents either a time on a 24 hour clock, or a precise date in the proleptic Gregorian calendar, optionally with a time and a time-zone offset. [GREGORIAN]

This element is intended as a way to encode modern dates and times in a machine-readable way so that, for example, user agents can offer to add birthday reminders or scheduled events to the user's calendar.

The time element is not intended for encoding times for which a precise date or time cannot be established. For example, it would be inappropriate for encoding times like "one millisecond after the big bang", "the early part of the Jurassic period", or "a winter around 250 BCE".

For dates before the introduction of the Gregorian calendar, authors are encouraged to not use the time element, or else to be very careful about converting dates and times from the period to the Gregorian calendar. This is complicated by the manner in which the Gregorian calendar was phased in, which occurred at different times in different countries, ranging from partway through the 16th century all the way to early in the 20th.

The pubdate attribute is a boolean attribute. If specified, it indicates that the date and time given by the element is the publication date and time of the nearest ancestor article element, or, if the element has no ancestor article element, of the document as a whole. If the element has a pubdate attribute specified, then the element needs a date. For each article element, there must no more than one time element with a pubdate attribute whose nearest ancestor is that article element. Furthermore, for each Document, there must be no more than one time element with a pubdate attribute that does not have an ancestor article element.

The datetime attribute, if present, gives the date or time being specified. Otherwise, the date or time is given by the element's contents.

If the element needs a date, and the datetime attribute is present, then the attribute's value must be a valid date string with optional time.

If the element needs a date, but the datetime attribute is not present, then the element's textContent must be a valid date string in content with optional time.

If the element does not need a date, and the datetime attribute is present, then the attribute's value must be a valid date or time string.

If the element does not need a date, but the datetime attribute is not present, then the element's textContent must be a valid date or time string in content.

The date, if any, must be expressed using the Gregorian calendar.

If the datetime attribute is present, the user agent should convey the attribute's value to the user when rendering the element.

The time element can be used to encode dates, for example in Microformats. The following shows a hypothetical way of encoding an event using a variant on hCalendar that uses the time element:

<div class="vevent">
 <a class="url" href="http://www.web2con.com/">http://www.web2con.com/</a>
  <span class="summary">Web 2.0 Conference</span>:
  <time class="dtstart" datetime="2007-10-05">October 5</time> -
  <time class="dtend" datetime="2007-10-20">19</time>,
  at the <span class="location">Argent Hotel, San Francisco, CA</span>
 </div>

The time element is not necessary for encoding dates or times. In the following snippet, the time is encoded using time, so that it can be restyled (e.g. using XBL2) to match local conventions, while the year is not marked up at all, since marking it up would not be particularly useful.

<p>I usually have a snack at <time>16:00</time>.</p>
<p>I've liked model trains since at least 1983.</p>

Using a styling technology that supports restyling times, the first paragraph from the above snippet could be rendered as follows:

I usually have a snack at 4pm.

Or it could be rendered as follows:

I usually have a snack at 16h00.

The dateTime IDL attribute must reflect the datetime content attribute.

The pubDate IDL attribute must reflect the pubdate content attribute.

User agents, to obtain the date, time, and time-zone offset represented by a time element, must follow these steps:

  1. If the datetime attribute is present, then use the rules to parse a date or time string with the flag in attribute from the value of that attribute, and let the result be result.
  2. Otherwise, use the rules to parse a date or time string with the flag in content from the element's textContent, and let the result be result.
  3. If result is empty (because the parsing failed), then the date is unknown, the time is unknown, and the time-zone offset is unknown.
  4. Otherwise: if result contains a date, then that is the date; if result contains a time, then that is the time; and if result contains a time-zone offset, then the time-zone offset is the element's time-zone offset. (A time-zone offset can only be present if both a date and a time are also present.)
time . valueAsDate

Returns a Date object representing the specified date and time.

The valueAsDate IDL attribute must return either null or a new Date object initialised to the relevant value as defined by the following list:

If the date is known but the time is not
The time corresponding to midnight UTC (i.e. the first second) of the given date.
If the time is known but the date is not
The time corresponding to the given time of 1970-01-01, with the time zone UTC.
If both the date and the time are known
The time corresponding to the date and time, with the given time-zone offset.
If neither the date nor the time are known
The null value.

When a Date object is to be returned, a new one must be constructed.

In the following snippet:

<p>Our first date was <time datetime="2006-09-23">a Saturday</time>.</p>

...the time element's valueAsDate attribute would have the value 1,158,969,600,000ms.

In the following snippet:

<p>Many people get up at <time>08:00</time>.</p>

...the time element's valueAsDate attribute would have the value 28,800,000ms.

In this example, an article's publication date is marked up using time:

<article>
 <h1>Small tasks</h1>
 <footer>Published <time pubdate>2009-08-30</time>.</footer>
 <p>I put a bike bell on his bike.</p>
</article>

Here is another way that could be marked up:

<article>
 <h1>Small tasks</h1>
 <footer>Published <time pubdate datetime="2009-08-30">today</time>.</footer>
 <p>I put a bike bell on his bike.</p>
</article>

Here is the same thing but with the time included. Because the element is empty, it will be replaced in the rendering with a more readable version of the date and time given.

<article>
 <h1>Small tasks</h1>
 <footer>Published <time pubdate datetime="2009-08-30T07:13Z"></time>.</footer>
 <p>I put a bike bell on his bike.</p>
</article>

3.6.10 The code element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The code element represents a fragment of computer code. This could be an XML element name, a filename, a computer program, or any other string that a computer would recognize.

Although there is no formal way to indicate the language of computer code being marked up, authors who wish to mark code elements with the language used, e.g. so that syntax highlighting scripts can use the right rules, may do so by adding a class prefixed with "language-" to the element.

The following example shows how the element can be used in a paragraph to mark up element names and computer code, including punctuation.

<p>The <code>code</code> element represents a fragment of computer
code.</p>

<p>When you call the <code>activate()</code> method on the
<code>robotSnowman</code> object, the eyes glow.</p>

<p>The example below uses the <code>begin</code> keyword to indicate
the start of a statement block. It is paired with an <code>end</code>
keyword, which is followed by the <code>.</code> punctuation character
(full stop) to indicate the end of the program.</p>

The following example shows how a block of code could be marked up using the pre and code elements.

<pre><code class="language-pascal">var i: Integer;
begin
   i := 1;
end.</code></pre>

A class is used in that example to indicate the language used.

See the pre element for more details.

3.6.11 The var element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The var element represents a variable. This could be an actual variable in a mathematical expression or programming context, or it could just be a term used as a placeholder in prose.

In the paragraph below, the letter "n" is being used as a variable in prose:

<p>If there are <var>n</var> pipes leading to the ice
cream factory then I expect at <em>least</em> <var>n</var>
flavors of ice cream to be available for purchase!</p>

For mathematics, in particular for anything beyond the simplest of expressions, MathML is more appropriate. However, the var element can still be used to refer to specific variables that are then mentioned in MathML expressions.

In this example, an equation is shown, with a legend that references the variables in the equation. The expression itself is marked up with MathML, but the variables are mentioned in the figure's legend using var.

<figure>
 <dd>
  <math>
   <mi>a</mi>
   <mo>=</mo>
   <msqrt>
    <msup><mi>b</mi><mn>2</mn></msup>
    <mi>+</mi>
    <msup><mi>c</mi><mn>2</mn></msup>
   </msqrt>
  </math>
 </dd>
 <dt>
  Using Pythagoras' theorem to solve for the hypotenuse <var>a</var> of
  a triangle with sides <var>b</var> and <var>c</var>
 </dt>
</figure>

3.6.12 The samp element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The samp element represents (sample) output from a program or computing system.

See the pre and kbd elements for more details.

This example shows the samp element being used inline:

<p>The computer said <samp>Too much cheese in tray
two</samp> but I didn't know what that meant.</p>

This second example shows a block of sample output. Nested samp and kbd elements allow for the styling of specific elements of the sample output using a style sheet.

<pre><samp><span class="prompt">jdoe@mowmow:~$</span> <kbd>ssh demo.example.com</kbd>
Last login: Tue Apr 12 09:10:17 2005 from mowmow.example.com on pts/1
Linux demo 2.6.10-grsec+gg3+e+fhs6b+nfs+gr0501+++p3+c4a+gr2b-reslog-v6.189 #1 SMP Tue Feb 1 11:22:36 PST 2005 i686 unknown

<span class="prompt">jdoe@demo:~$</span> <span class="cursor">_</span></samp></pre>

3.6.13 The kbd element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The kbd element represents user input (typically keyboard input, although it may also be used to represent other input, such as voice commands).

When the kbd element is nested inside a samp element, it represents the input as it was echoed by the system.

When the kbd element contains a samp element, it represents input based on system output, for example invoking a menu item.

When the kbd element is nested inside another kbd element, it represents an actual key or other single unit of input as appropriate for the input mechanism.

Here the kbd element is used to indicate keys to press:

<p>To make George eat an apple, press <kbd><kbd>Shift</kbd>+<kbd>F3</kbd></kbd></p>

In this second example, the user is told to pick a particular menu item. The outer kbd element marks up a block of input, with the inner kbd elements representing each individual step of the input, and the samp elements inside them indicating that the steps are input based on something being displayed by the system, in this case menu labels:

<p>To make George eat an apple, select
    <kbd><kbd><samp>File</samp></kbd>|<kbd><samp>Eat Apple...</samp></kbd></kbd>
</p>

Such precision isn't necessary; the following is equally fine:

<p>To make George eat an apple, select <kbd>File | Eat Apple...</kbd></p>

3.6.14 The sub and sup elements

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which these elements may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Use HTMLElement.

The sup element represents a superscript and the sub element represents a subscript.

These elements must be used only to mark up typographical conventions with specific meanings, not for typographical presentation for presentation's sake. For example, it would be inappropriate for the sub and sup elements to be used in the name of the LaTeX document preparation system. In general, authors should use these elements only if the absence of those elements would change the meaning of the content.

In certain languages, superscripts are part of the typographical conventions for some abbreviations.

<p>The most beautiful women are
<span lang="fr"><abbr>M<sup>lle</sup></abbr> Gwendoline</span> and
<span lang="fr"><abbr>M<sup>me</sup></abbr> Denise</span>.</p>

The sub element can be used inside a var element, for variables that have subscripts.

Here, the sub element is used to represents the subscript that identifies the variable in a family of variables:

<p>The coordinate of the <var>i</var>th point is
(<var>x<sub><var>i</var></sub></var>, <var>y<sub><var>i</var></sub></var>).
For example, the 10th point has coordinate
(<var>x<sub>10</sub></var>, <var>y<sub>10</sub></var>).</p>

Mathematical expressions often use subscripts and superscripts. Authors are encouraged to use MathML for marking up mathematics, but authors may opt to use sub and sup if detailed mathematical markup is not desired. [MATHML]

<var>E</var>=<var>m</var><var>c</var><sup>2</sup>
f(<var>x</var>, <var>n</var>) = log<sub>4</sub><var>x</var><sup><var>n</var></sup>

3.6.15 The i element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The i element represents a span of text in an alternate voice or mood, or otherwise offset from the normal prose, such as a taxonomic designation, a technical term, an idiomatic phrase from another language, a thought, a ship name, or some other prose whose typical typographic presentation is italicized.

Terms in languages different from the main text should be annotated with lang attributes (or, in XML, lang attributes in the XML namespace).

The examples below show uses of the i element:

<p>The <i class="taxonomy">Felis silvestris catus</i> is cute.</p>
<p>The term <i>prose content</i> is defined above.</p>
<p>There is a certain <i lang="fr">je ne sais quoi</i> in the air.</p>

In the following example, a dream sequence is marked up using i elements.

<p>Raymond tried to sleep.</p>
<p><i>The ship sailed away on Thursday</i>, he
dreamt. <i>The ship had many people aboard, including a beautiful
princess called Carey. He watched her, day-in, day-out, hoping she
would notice him, but she never did.</i></p>
<p><i>Finally one night he picked up the courage to speak with
her—</i></p>
<p>Raymond woke with a start as the fire alarm rang out.</p>

Authors are encouraged to use the class attribute on the i element to identify why the element is being used, so that if the style of a particular use (e.g. dream sequences as opposed to taxonomic terms) is to be changed at a later date, the author doesn't have to go through the entire document (or series of related documents) annotating each use. Similarly, authors are encouraged to consider whether other elements might be more applicable than the i element, for instance the em element for marking up stress emphasis, or the dfn element to mark up the defining instance of a term.

Style sheets can be used to format i elements, just like any other element can be restyled. Thus, it is not the case that content in i elements will necessarily be italicized.

3.6.16 The b element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The b element represents a span of text to be stylistically offset from the normal prose without conveying any extra importance, such as key words in a document abstract, product names in a review, or other spans of text whose typical typographic presentation is boldened.

The following example shows a use of the b element to highlight key words without marking them up as important:

<p>The <b>frobonitor</b> and <b>barbinator</b> components are fried.</p>

In the following example, objects in a text adventure are highlighted as being special by use of the b element.

<p>You enter a small room. Your <b>sword</b> glows
brighter. A <b>rat</b> scurries past the corner wall.</p>

Another case where the b element is appropriate is in marking up the lede (or lead) sentence or paragraph. The following example shows how a BBC article about kittens adopting a rabbit as their own could be marked up:

<article>
 <h2>Kittens 'adopted' by pet rabbit</h2>
 <p><b>Six abandoned kittens have found an unexpected new
 mother figure — a pet rabbit.</b></p>
 <p>Veterinary nurse Melanie Humble took the three-week-old
 kittens to her Aberdeen home.</p>
[...]

The b element should be used as a last resort when no other element is more appropriate. In particular, headings should use the h1 to h6 elements, stress emphasis should use the em element, importance should be denoted with the strong element, and text marked or highlighted should use the mark element.

The following would be incorrect usage:

<p><b>WARNING!</b> Do not frob the barbinator!</p>

In the previous example, the correct element to use would have been strong, not b.

Style sheets can be used to format b elements, just like any other element can be restyled. Thus, it is not the case that content in b elements will necessarily be boldened.

3.6.17 The mark element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The mark element represents a run of text in one document marked or highlighted for reference purposes, due to its relevance in another context. When used in a quotation or other block of text referred to from the prose, it indicates a highlight that was not originally present but which has been added to bring the reader's attention to a part of the text that might not have been considered important by the original author when the block was originally written, but which is now under previously unexpected scrutiny. When used in the main prose of a document, it indicates a part of the document that has been highlighted due to its likely relevance to the user's current activity.

This example shows how the mark element can be used to bring attention to a particular part of a quotation:

<p lang="en-US">Consider the following quote:</p>
<blockquote lang="en-GB">
 <p>Look around and you will find, no-one's really
 <mark>colour</mark> blind.</p>
</blockquote>
<p lang="en-US">As we can tell from the <em>spelling</em> of the word,
the person writing this quote is clearly not American.</p>

Another example of the mark element is highlighting parts of a document that are matching some search string. If someone looked at a document, and the server knew that the user was searching for the word "kitten", then the server might return the document with one paragraph modified as follows:

<p>I also have some <mark>kitten</mark>s who are visiting me
these days. They're really cute. I think they like my garden! Maybe I
should adopt a <mark>kitten</mark>.</p>

In the following snippet, a paragraph of text refers to a specific part of a code fragment.

<p>The highlighted part below is where the error lies:</p>
<pre><code>var i: Integer;
begin
   i := <mark>1.1</mark>;
end.</code></pre>

This is another example showing the use of mark to highlight a part of quoted text that was originally not emphasized. In this example, common typographic conventions have led the author to explicitly style mark elements in quotes to render in italics.

<article>
 <style scoped>
  blockquote mark, q mark {
    font: inherit; font-style: italic;
    text-decoration: none;
    background: transparent; color: inherit;
  }
  .bubble em {
    font: inherit; font-size: larger;
    text-decoration: underline;
  }
 </style>
 <h1>She knew</h1>
 <p>Did you notice the subtle joke in the joke on panel 4?</p>
 <blockquote>
  <p class="bubble">I didn't <em>want</em> to believe. <mark>Of course
  on some level I realized it was a known-plaintext attack.</mark> But I
  couldn't admit it until I saw for myself.</p>
 </blockquote>
 <p>(Emphasis mine.) I thought that was great. It's so pedantic, yet it
 explains everything neatly.</p>
</article>

Note, incidentally, the distinction between the em element in this example, which is part of the original text being quoted, and the mark element, which is highlighting a part for comment.

The following example shows the difference between denoting the importance of a span of text (strong) as opposed to denoting the relevance of a span of text (mark). It is an extract from a textbook, where the extract has had the parts relevant to the exam highlighted. The safety warnings, important though they may be, are apparently not relevant to the exam.

<h3>Wormhole Physics Introduction</h3>

<p><mark>A wormhole in normal conditions can be held open for a
maximum of just under 39 minutes.</mark> Conditions that can increase
the time include a powerful energy source coupled to one or both of
the gates connecting the wormhole, and a large gravity well (such as a
black hole).</p>

<p><mark>Momentum is preserved across the wormhole. Electromagnetic
radiation can travel in both directions through a wormhole,
but matter cannot.</mark></p>

<p>When a wormhole is created, a vortex normally forms.
<strong>Warning: The vortex caused by the wormhole opening will
annihilate anything in its path.</strong> Vortexes can be avoided when
using sufficiently advanced dialing technology.</p>

<p><mark>An obstruction in a gate will prevent it from accepting a
wormhole connection.</mark></p>

3.6.18 The ruby element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
One or more groups of: phrasing content followed either by a single rt element, or an rp element, an rt element, and another rp element.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The ruby element allows one or more spans of phrasing content to be marked with ruby annotations. Ruby annotations are short runs of text presented alongside base text, primarily used in East Asian typography as a guide for pronunciation or to include other annotations. In Japanese, this form of typography is also known as furigana.

A ruby element represents the spans of phrasing content it contains, ignoring all the child rt and rp elements and their descendants. Those spans of phrasing content have associated annotations created using the rt element.

In this example, each ideograph in the Japanese text 漢字 is annotated with its reading in hiragana.

...
<ruby>
 漢 <rt> かん </rt>
 字 <rt> じ  </rt>
</ruby>
...

This might be rendered as:

The two main ideographs, each with its annotation in hiragana rendered in a smaller font above it.

In this example, each ideograph in the traditional Chinese text 漢字 is annotated with its bopomofo reading.

<ruby>
 漢 <rt> ㄏㄢˋ </rt>
 字 <rt> ㄗˋ  </rt>
</ruby>

This might be rendered as:

The two main ideographs, each with its bopomofo annotation rendered in a smaller font next to it.

In this example, each ideograph in the simplified Chinese text 汉字 is annotated with its pinyin reading.

...
<ruby>
 汉 <rt> hàn </rt>
 字 <rt> zì  </rt>
</ruby>
...

This might be rendered as:

The two main ideographs, each with its pinyin annotation rendered in a smaller font above it.

3.6.19 The rt element

Status: Last call for comments

Categories
None.
Contexts in which this element may be used:
As a child of a ruby element.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The rt element marks the ruby text component of a ruby annotation.

An rt element that is a child of a ruby element represents an annotation (given by its children) for the zero or more nodes of phrasing content that immediately precedes it in the ruby element, ignoring rp elements.

An rt element that is not a child of a ruby element represents the same thing as its children.

3.6.20 The rp element

Status: Last call for comments

Categories
None.
Contexts in which this element may be used:
As a child of a ruby element, either immediately before or immediately after an rt element.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The rp element can be used to provide parentheses around a ruby text component of a ruby annotation, to be shown by user agents that don't support ruby annotations.

An rp element that is a child of a ruby element represents nothing and its contents must be ignored. An rp element whose parent element is not a ruby element represents its children.

The example above, in which each ideograph in the text 漢字 is annotated with its kanji reading, could be expanded to use rp so that in legacy user agents the readings are in parentheses:

...
<ruby>
 漢 <rp>(</rp><rt>かん</rt><rp>)</rp>
 字 <rp>(</rp><rt>じ</rt><rp>)</rp>
</ruby>
...

In conforming user agents the rendering would be as above, but in user agents that do not support ruby, the rendering would be:

... 漢 (かん) 字 (じ) ...

3.6.21 The bdo element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
Also, the dir global attribute has special semantics on this element.
DOM interface:
Uses HTMLElement.

The bdo element represents explicit text directionality formatting control for its children. It allows authors to override the Unicode bidirectional algorithm by explicitly specifying a direction override. [BIDI]

Authors must specify the dir attribute on this element, with the value ltr to specify a left-to-right override and with the value rtl to specify a right-to-left override.

If the element has the dir attribute set to the exact value ltr, then for the purposes of the bidi algorithm, the user agent must act as if there was a U+202D LEFT-TO-RIGHT OVERRIDE character at the start of the element, and a U+202C POP DIRECTIONAL FORMATTING at the end of the element.

If the element has the dir attribute set to the exact value rtl, then for the purposes of the bidi algorithm, the user agent must act as if there was a U+202E RIGHT-TO-LEFT OVERRIDE character at the start of the element, and a U+202C POP DIRECTIONAL FORMATTING at the end of the element.

The requirements on handling the bdo element for the bidi algorithm may be implemented indirectly through the style layer. For example, an HTML+CSS user agent should implement these requirements by implementing the CSS 'unicode-bidi' property. [CSS]

3.6.22 The span element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
interface HTMLSpanElement : HTMLElement {};

The span element doesn't mean anything on its own, but can be useful when used together with other attributes, e.g. class, lang, or dir. It represents its children.

In this example, a code fragment is marked up using span elements and class attributes so that its keywords and identifiers can be color-coded from CSS:

<pre><code class="lang-c"><span class="keyword">for</span> (<span class="ident">j</span> = 0; <span class="ident">j</span> &lt; 256; <span class="ident">j</span>++) {
  <span class="ident">i_t3</span> = (<span class="ident">i_t3</span> & 0x1ffff) | (<span class="ident">j</span> &lt;&lt; 17);
  <span class="ident">i_t6</span> = (((((((<span class="ident">i_t3</span> >> 3) ^ <span class="ident">i_t3</span>) >> 1) ^ <span class="ident">i_t3</span>) >> 8) ^ <span class="ident">i_t3</span>) >> 5) & 0xff;
  <span class="keyword">if</span> (<span class="ident">i_t6</span> == <span class="ident">i_t1</span>)
    <span class="keyword">break</span>;
}</code></pre>

3.6.23 Usage summary

Status: Last call for comments

This section is non-normative.

Element Purpose Example
a Hyperlinks
Visit my <a href="drinks.html">drinks</a> page.
em Stress emphasis
I must say I <em>adore</em> lemonade.
strong Importance
This tea is <strong>very hot</strong>.
small Side comments
These grapes are made into wine. <small>Alcohol is addictive.</small>
cite Titles of works
The case <cite>Hugo v. Danielle</cite> is relevant here.
q Quotations
The judge said <q>You can drink water from the fish tank</q> but advised against it.
dfn Defining instance
The term <dfn>organic food</dfn> refers to food produced without synthetic chemicals.
abbr Abbreviations
Organic food in Ireland is certified by the <abbr title="Irish Organic Farmers and Growers Association">IOFGA</abbr>.
time Date and/or time
Published <time>2009-10-21</time>.
code Computer code
The <code>fruitdb</code> program can be used for tracking fruit production.
var Variables
If there are <var>n</var> fruit in the bowl, at least <var>n</var>÷2 will be ripe.
samp Computer output
The computer said <samp>Unknown error -3</samp>.
kbd User input
Hit <kbd>F1</kbd> to continue.
sub Subscripts
Water is H<sub>2</sub>O.
sup Superscripts
The Hydrogen in heavy water is usually <sup>2</sup>H.
i Alternative voice
Lemonade consists primarily of <i>Citrus limon</i>.
b Keywords
Take a <b>lemon</b> and squeeze it with a <b>juicer</b>.
mark Highlight
Elderflower cordial, with one <mark>part</mark> cordial to ten <mark>part</mark>s water, stands a<mark>part</mark> from the rest.
ruby, rt, rp Ruby annotations
<ruby> OJ <rp>(<rt>Orange Juice<rp>)</ruby>
bdo Text directionality formatting
The proposal is to write English, but in reverse order. "Juice" would become "<bdo dir=rtl>Juice</bdo>"
span Other
In French we call it <span lang="fr">sirop de sureau</span>.

3.7 Edits

Status: Last call for comments

The ins and del elements represent edits to the document.

3.7.1 The ins element

Status: Last call for comments

Categories
Flow content.
When the element only contains phrasing content: phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Transparent.
Content attributes:
Global attributes
cite
datetime
DOM interface:
Uses the HTMLModElement interface.

The ins element represents an addition to the document.

The following represents the addition of a single paragraph:

<aside>
 <ins>
  <p> I like fruit. </p>
 </ins>
</aside>

As does this, because everything in the aside element here counts as phrasing content and therefore there is just one paragraph:

<aside>
 <ins>
  Apples are <em>tasty</em>.
 </ins>
 <ins>
  So are pears.
 </ins>
</aside>

ins elements should not cross implied paragraph boundaries.

The following example represents the addition of two paragraphs, the second of which was inserted in two parts. The first ins element in this example thus crosses a paragraph boundary, which is considered poor form.

<aside>
 <!-- don't do this -->
 <ins datetime="2005-03-16T00:00Z">
  <p> I like fruit. </p>
  Apples are <em>tasty</em>.
 </ins>
 <ins datetime="2007-12-19T00:00Z">
  So are pears.
 </ins>
</aside>

Here is a better way of marking this up. It uses more elements, but none of the elements cross implied paragraph boundaries.

<aside>
 <ins datetime="2005-03-16T00:00Z">
  <p> I like fruit. </p>
 </ins>
 <ins datetime="2005-03-16T00:00Z">
  Apples are <em>tasty</em>.
 </ins>
 <ins datetime="2007-12-19T00:00Z">
  So are pears.
 </ins>
</aside>

3.7.2 The del element

Status: Last call for comments

Categories
Flow content.
When the element only contains phrasing content: phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Transparent.
Content attributes:
Global attributes
cite
datetime
DOM interface:
Uses the HTMLModElement interface.

The del element represents a removal from the document.

del elements should not cross implied paragraph boundaries.

The following shows a "to do" list where items that have been done are crossed-off with the date and time of their completion.

<h1>To Do</h1>
<ul>
 <li>Empty the dishwasher</li>
 <li><del datetime="2009-10-11T01:25-07:00">Watch Walter Lewin's lectures</del></li>
 <li><del datetime="2009-10-10T23:38-07:00">Download more tracks</del></li>
 <li>Buy a printer</li>
</ul>

3.7.3 Attributes common to ins and del elements

Status: Last call for comments

The cite attribute may be used to specify the address of a document that explains the change. When that document is long, for instance the minutes of a meeting, authors are encouraged to include a fragment identifier pointing to the specific part of that document that discusses the change.

If the cite attribute is present, it must be a valid URL that explains the change. To obtain the corresponding citation link, the value of the attribute must be resolved relative to the element. User agents should allow users to follow such citation links.

The datetime attribute may be used to specify the time and date of the change.

If present, the datetime attribute must be a valid global date and time string value.

User agents must parse the datetime attribute according to the parse a global date and time string algorithm. If that doesn't return a time, then the modification has no associated timestamp (the value is non-conforming; it is not a valid global date and time string). Otherwise, the modification is marked as having been made at the given datetime. User agents should use the associated time-zone offset information to determine which time zone to present the given datetime in.

The ins and del elements must implement the HTMLModElement interface:

interface HTMLModElement : HTMLElement {
           attribute DOMString cite;
           attribute DOMString dateTime;
};

The cite IDL attribute must reflect the element's cite content attribute. The dateTime IDL attribute must reflect the element's datetime content attribute.

3.7.4 Edits and paragraphs

Status: Last call for comments

This section is non-normative.

Since the ins and del elements do not affect paragraphing, it is possible, in some cases where paragraphs are implied (without explicit p elements), for an ins or del element to span both an entire paragraph or other non-phrasing content elements and part of another paragraph. For example:

<section>
 <ins>
  <p>
   This is a paragraph that was inserted.
  </p>
  This is another paragraph whose first sentence was inserted
  at the same time as the paragraph above.
 </ins>
 This is a second sentence, which was there all along.
</section>

By only wrapping some paragraphs in p elements, one can even get the end of one paragraph, a whole second paragraph, and the start of a third paragraph to be covered by the same ins or del element (though this is very confusing, and not considered good practice):

<section>
 This is the first paragraph. <ins>This sentence was
 inserted.
 <p>This second paragraph was inserted.</p>
 This sentence was inserted too.</ins> This is the
 third paragraph in this example.
 <!-- (don't do this) -->
</section>

However, due to the way implied paragraphs are defined, it is not possible to mark up the end of one paragraph and the start of the very next one using the same ins or del element. You instead have to use one (or two) p element(s) and two ins or del elements, as for example:

<section>
 <p>This is the first paragraph. <del>This sentence was
 deleted.</del></p>
 <p><del>This sentence was deleted too.</del> That
 sentence needed a separate &lt;del&gt; element.</p>
</section>

Partly because of the confusion described above, authors are strongly encouraged to always mark up all paragraphs with the p element, instead of having ins or del elements that cross implied paragraphs boundaries.

3.7.5 Edits and lists

Status: Last call for comments

This section is non-normative.

The content models of the ol and ul elements do not allow ins and del elements as children. Lists always represent all their items, including items that would otherwise have been marked as deleted.

To indicate that an item is inserted or deleted, an ins or del element can be wrapped around the contents of the li element. To indicate that an item has been replaced by another, a single li element can have one or more del elements followed by one or more ins elements.

In the following example, a list that started empty had items added and removed from it over time. The bits in the example that have been emphasized show the parts that are the "current" state of the list. The list item numbers don't take into account the edits, though.

<h1>Stop-ship bugs</h1>
<ol>
 <li><ins datetime="2008-02-12T15:20Z">Bug 225:
 Rain detector doesn't work in snow</ins></li>
 <li><del datetime="2008-03-01T20:22Z"><ins datetime="2008-02-14T12:02Z">Bug 228:
 Water buffer overflows in April</ins></del></li>
 <li><ins datetime="2008-02-16T13:50Z">Bug 230:
 Water heater doesn't use renewable fuels</ins></li>
 <li><del datetime="2008-02-20T21:15Z"><ins datetime="2008-02-16T14:25Z">Bug 232:
 Carbon dioxide emissions detected after startup</ins></del></li>
</ol>

In the following example, a list that started with just fruit was replaced by a list with just colors.

<h1>List of <del>fruits</del><ins>colors</ins></h1>
<ul>
 <li><del>Lime</del><ins>Green</ins></li>
 <li><del>Apple</del></li>
 <li>Orange</li>
 <li><del>Pear</del></li>
 <li><ins>Teal</ins></li>
 <li><del>Lemon</del><ins>Yellow</ins></li>
 <li>Olive</li>
 <li><ins>Purple</ins>
</ul>

3.8 Embedded content

Status: Last call for comments

3.8.1 The figure element

Status: Last call for comments

Categories
Flow content.
Sectioning root.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
In any order, one dd element, and optionally one dt element.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The figure element represents some flow content, optionally with a caption, that is self-contained and is typically referenced as a single unit from the main flow of the document.

The element can thus be used to annotate illustrations, diagrams, photos, code listings, etc, that are referred to from the main content of the document, but that could, without affecting the flow of the document, be moved away from that primary content, e.g. to the side of the page, to dedicated pages, or to an appendix.

The first dt element child of the element, if any, represents the caption of the figure element's contents. If there is no child dt element, then there is no caption.

The first dd element child of the element, if any, represents the element's contents. If there is no child dd element, then there are no contents.

This example shows the figure element to mark up a code listing.

<p>In <a href="#l4">listing 4</a> we see the primary core interface
API declaration.</p>
<figure id="l4">
 <dt>Listing 4. The primary core interface API declaration.</dt>
 <dd>
  <pre><code>interface PrimaryCore {
  boolean verifyDataLine();
  void sendData(in sequence&lt;byte> data);
  void initSelfDestruct();
}</code></pre>
 </dd>
</figure>
<p>The API is designed to use UTF-8.</p>

Here we see a figure element to mark up a photo.

<figure>
 <dd>
  <img src="bubbles-work.jpeg"
       alt="Bubbles, sitting in his office chair, works on his
            latest project intently.">
 </dd>
 <dt>Bubbles at work</dt>
</figure>

In this example, we see an image that is not a figure, as well as an image and a video that are.

<h2>Malinko's comics</h2>

<p>This case centered on some sort of "intellectual property"
infringement related to a comic (see Exhibit A). The suit started
after a trailer ending with these words:

<blockquote>
 <img src="promblem-packed-action.png" alt="ROUGH COPY! Promblem-Packed Action!">
</blockquote>

<p>...was aired. A lawyer, armed with a Bigger Notebook, launched a
preemptive strike using snowballs. A complete copy of the trailer is
included with Exhibit B.

<figure>
 <dd><img src="ex-a.png" alt="Two squiggles on a dirty piece of paper.">
 <dt>Exhibit A. The alleged <cite>rough copy</cite> comic.
</figure>

<figure>
 <dd><video src="ex-b.mov"></video>
 <dt>Exhibit B. The <cite>Rough Copy</cite> trailer.
</figure>

<p>The case was resolved out of court.

Here, a part of a poem is marked up using figure.

<figure>
 <dd>
  <p>'Twas brillig, and the slithy toves<br>
  Did gyre and gimble in the wabe;<br>
  All mimsy were the borogoves,<br>
  And the mome raths outgrabe.</p>
 </dd>
 <dt><cite>Jabberwocky</cite> (first verse). Lewis Carroll, 1832-98</dt>
</figure>

In this example, which could be part of a much larger work discussing a castle, the figure has three images in it.

<figure>
 <dd>
  <img src="castle1423.jpeg" title="Etching. Anonymous, ca. 1423."
       alt="The castle has one tower, and a tall wall around it.">
  <img src="castle1858.jpeg" title="Oil-based paint on canvas. Maria Towle, 1858."
       alt="The castle now has two towers and two walls.">
  <img src="castle1999.jpeg" title="Film photograph. Peter Jankle, 1999."
       alt="The castle lies in ruins, the original tower all that remains in one piece.">
 </dd>
 <dt>The castle through the ages: 1423, 1858, and 1999 respectively.</dt>
</figure>

3.8.2 The img element

Status: Last call for comments. ISSUE-30 (longdesc) and ISSUE-66 (image-analysis) block progress to Last Call

Categories
Flow content.
Phrasing content.
Embedded content.
If the element has a usemap attribute: Interactive content.
Contexts in which this element may be used:
Where embedded content is expected.
Content model:
Empty.
Content attributes:
Global attributes
alt
src
usemap
ismap
width
height
DOM interface:
[NamedConstructor=Image(),
 NamedConstructor=Image(in unsigned long width),
 NamedConstructor=Image(in unsigned long width, in unsigned long height)]
interface HTMLImageElement : HTMLElement {
           attribute DOMString alt;
           attribute DOMString src;
           attribute DOMString useMap;
           attribute boolean isMap;
           attribute unsigned long width;
           attribute unsigned long height;
  readonly attribute unsigned long naturalWidth;
  readonly attribute unsigned long naturalHeight;
  readonly attribute boolean complete;
};

An img element represents an image.

The image given by the src attribute is the embedded content, and the value of the alt attribute is the img element's fallback content.

The src attribute must be present, and must contain a valid URL referencing a non-interactive, optionally animated, image resource that is neither paged nor scripted. If the base URI of the element is the same as the document's address, then the src attribute's value must not be the empty string.

Images can thus be static bitmaps (e.g. PNGs, GIFs, JPEGs), single-page vector documents (single-page PDFs, XML files with an SVG root element), animated bitmaps (APNGs, animated GIFs), animated vector graphics (XML files with an SVG root element that use declarative SMIL animation), and so forth. However, this also precludes SVG files with script, multipage PDF files, interactive MNG files, HTML documents, plain text documents, and so forth.

The requirements on the alt attribute's value are described in the next section.

The img must not be used as a layout tool. In particular, img elements should not be used to display transparent images, as they rarely convey meaning and rarely add anything useful to the document.


Unless the user agent cannot support images, or its support for images has been disabled, or the user agent only fetches elements on demand, or the element's src attribute has a value that is an ignored self-reference, then, when an img is created with a src attribute, and whenever the src attribute is set subsequently, the user agent must resolve the value of that attribute, relative to the element, and if that is successful must then fetch that resource.

The src attribute's value is an ignored self-reference if its value is the empty string, and the base URI of the element is the same as the document's address.

Fetching the image must delay the load event of the element's document until the task that is queued by the networking task source once the resource has been fetched (defined below) has been run.

This, unfortunately, can be used to perform a rudimentary port scan of the user's local network (especially in conjunction with scripting, though scripting isn't actually necessary to carry out such an attack). User agents may implement cross-origin access control policies that mitigate this attack.

If the image is in a supported image type and its dimensions are known, then the image is said to be available (this affects exactly what the element represents, as defined below). This can be true even before the image is completely downloaded, if the user agent supports incremental rendering of images; in such cases, each task that is queued by the networking task source while the image is being fetched must update the presentation of the image appropriately. It can also stop being true, e.g. if the user agent finds, after obtaining the image's dimensions, that the image data is actually fatally corrupted.

If the image was not fetched (e.g. because the UA's image support is disabled, or because the src attribute's value is an ignored self-reference), or if the conditions in the previous paragraph are not met, then the image is not available.

An image might be available in one view but not another. For instance, a Document could be rendered by a screen reader providing a speech synthesis view of the output of a Web browser using the screen media. In this case, the image would be available in the Web browser's screen view, but not available in the screen reader's view.

Whether the image is fetched successfully or not (e.g. whether the response code was a 2xx code or equivalent) must be ignored when determining the image's type and whether it is a valid image.

This allows servers to return images with error responses, and have them displayed.

The user agents should apply the image sniffing rules to determine the type of the image, with the image's associated Content-Type headers giving the official type. If these rules are not applied, then the type of the image must be the type given by the image's associated Content-Type headers.

User agents must not support non-image resources with the img element (e.g. XML files whose root element is an HTML element). User agents must not run executable code (e.g. scripts) embedded in the image resource. User agents must only display the first page of a multipage resource (e.g. a PDF file). User agents must not allow the resource to act in an interactive fashion, but should honor any animation in the resource.

This specification does not specify which image types are to be supported.

The task that is queued by the networking task source once the resource has been fetched, must act as appropriate given the following alternatives:

If the download was successful and the image is available
Queue a task to fire a simple event named load at the img element (this happens after complete starts returning true).
Otherwise (the fetching process failed without a response from the remote server, or completed but the image is not a supported image)
Queue a task to fire a simple event named error on the img element.

The task source for these tasks is the DOM manipulation task source.


What an img element represents depends on the src attribute and the alt attribute.

If the src attribute is set and the alt attribute is set to the empty string

The image is either decorative or supplemental to the rest of the content, redundant with some other information in the document.

If the image is available and the user agent is configured to display that image, then the element represents the image specified by the src attribute.

Otherwise, the element represents nothing, and may be omitted completely from the rendering. User agents may provide the user with a notification that an image is present but has been omitted from the rendering.

If the src attribute is set and the alt attribute is set to a value that isn't empty

The image is a key part of the content; the alt attribute gives a textual equivalent or replacement for the image.

If the image is available and the user agent is configured to display that image, then the element represents the image specified by the src attribute.

Otherwise, the element represents the text given by the alt attribute. User agents may provide the user with a notification that an image is present but has been omitted from the rendering.

If the src attribute is set and the alt attribute is not

The image might be a key part of the content, and there is no textual equivalent of the image available.

In a conforming document, the absence of the alt attribute indicates that the image is a key part of the content but that a textual replacement for the image was not available when the image was generated.

If the image is available, the element represents the image specified by the src attribute.

If the image is not available or if the user agent is not configured to display the image, then the user agent should display some sort of indicator that there is an image that is not being rendered, and may, if requested by the user, or if so configured, or when required to provide contextual information in response to navigation, provide caption information for the image, derived as follows:

  1. If the image has a title attribute whose value is not the empty string, then the value of that attribute is the caption information; abort these steps.

  2. If the image is the child of a figure element that has a child dt element, then the contents of the first such dt element are the caption information; abort these steps.

  3. Run the algorithm to create the outline for the document.

  4. If the img element did not end up associated with a heading in the outline, or if there are any other images that are lacking an alt attribute and that are associated with the same heading in the outline as the img element in question, then there is no caption information; abort these steps.

  5. The caption information is the heading with which the image is associated according to the outline.

If the src attribute is not set and either the alt attribute is set to the empty string or the alt attribute is not set at all

The element represents nothing.

Otherwise

The element represents the text given by the alt attribute.

The alt attribute does not represent advisory information. User agents must not present the contents of the alt attribute in the same way as content of the title attribute.

User agents may always provide the user with the option to display any image, or to prevent any image from being displayed. User agents may also apply image analysis heuristics to help the user make sense of the image when the user is unable to make direct use of the image, e.g. due to a visual disability or because they are using a text terminal with no graphics capabilities.

The contents of img elements, if any, are ignored for the purposes of rendering.


The usemap attribute, if present, can indicate that the image has an associated image map.

The ismap attribute, when used on an element that is a descendant of an a element with an href attribute, indicates by its presence that the element provides access to a server-side image map. This affects how events are handled on the corresponding a element.

The ismap attribute is a boolean attribute. The attribute must not be specified on an element that does not have an ancestor a element with an href attribute.

The img element supports dimension attributes.

The IDL attributes alt, src, useMap, and isMap each must reflect the respective content attributes of the same name.

image . width [ = value ]
image . height [ = value ]

These attributes return the actual rendered dimensions of the image, or zero if the dimensions are not known.

They can be set, to change the corresponding content attributes.

image . naturalWidth
image . naturalHeight

These attributes return the intrinsic dimensions of the image, or zero if the dimensions are not known.

image . complete

Returns true if the image has been downloaded, decoded, and found to be valid; otherwise, returns false.

image = new Image( [ width [, height ] ] )

Returns a new img element, with the width and height attributes set to the values passed in the relevant arguments, if applicable.

The IDL attributes width and height must return the rendered width and height of the image, in CSS pixels, if the image is being rendered, and is being rendered to a visual medium; or else the intrinsic width and height of the image, in CSS pixels, if the image is available but not being rendered to a visual medium; or else 0, if the image is not available. [CSS]

On setting, they must act as if they reflected the respective content attributes of the same name.

The IDL attributes naturalWidth and naturalHeight must return the intrinsic width and height of the image, in CSS pixels, if the image is available, or else 0. [CSS]

The IDL attribute complete must return true if the user agent has fetched the image specified in the src attribute, and it is in a supported image type (i.e. it was decoded without fatal errors), even if the final task queued by the networking task source for the fetching of the image resource has not yet been processed. Otherwise, the attribute must return false.

The value of complete can thus change while a script is executing.

Three constructors are provided for creating HTMLImageElement objects (in addition to the factory methods from DOM Core such as createElement()): Image(), Image(width), and Image(width, height). When invoked as constructors, these must return a new HTMLImageElement object (a new img element). If the width argument is present, the new object's width content attribute must be set to width. If the height argument is also present, the new object's height content attribute must be set to height. The element's document must be the active document of the browsing context of the Window object on which the interface object of the invoked constructor is found.

A single image can have different appropriate alternative text depending on the context.

In each of the following cases, the same image is used, yet the alt text is different each time. The image is the coat of arms of the Carouge municipality in the canton Geneva in Switzerland.

Here it is used as a supplementary icon:

<p>I lived in <img src="carouge.svg" alt=""> Carouge.</p>

Here it is used as an icon representing the town:

<p>Home town: <img src="carouge.svg" alt="Carouge"></p>

Here it is used as part of a text on the town:

<p>Carouge has a coat of arms.</p>
<p><img src="carouge.svg" alt="The coat of arms depicts a lion, sitting in front of a tree."></p>
<p>It is used as decoration all over the town.</p>

Here it is used as a way to support a similar text where the description is given as well as, instead of as an alternative to, the image:

<p>Carouge has a coat of arms.</p>
<p><img src="carouge.svg" alt=""></p>
<p>The coat of arms depicts a lion, sitting in front of a tree.
It is used as decoration all over the town.</p>

Here it is used as part of a story:

<p>He picked up the folder and a piece of paper fell out.</p>
<p><img src="carouge.svg" alt="Shaped like a shield, the paper had a
red background, a green tree, and a yellow lion with its tongue
hanging out and whose tail was shaped like an S."></p>
<p>He stared at the folder. S! The answer he had been looking for all
this time was simply the letter S! How had he not seen that before? It all
came together now. The phone call where Hector had referred to a lion's tail,
the time Marco had stuck his tongue out...</p>

Here it is not known at the time of publication what the image will be, only that it will be a coat of arms of some kind, and thus no replacement text can be provided, and instead only a brief caption for the image is provided, in the title attribute:

<p>The last user to have uploaded a coat of arms uploaded this one:</p>
<p><img src="last-uploaded-coat-of-arms.cgi" title="User-uploaded coat of arms."></p>

Ideally, the author would find a way to provide real replacement text even in this case, e.g. by asking the previous user. Not providing replacement text makes the document more difficult to use for people who are unable to view images, e.g. blind users, or users or very low-bandwidth connections or who pay by the byte, or users who are forced to use a text-only Web browser.

Here are some more examples showing the same picture used in different contexts, with different appropriate alternate texts each time.

<article>
 <h1>My cats</h1>
 <h2>Fluffy</h2>
 <p>Fluffy is my favorite.</p>
 <img src="fluffy.jpg" alt="She likes playing with a ball of yarn.">
 <p>She's just too cute.</p>
 <h2>Miles</h2>
 <p>My other cat, Miles just eats and sleeps.</p>
</article>
<article>
 <h1>Photography</h1>
 <h2>Shooting moving targets indoors</h2>
 <p>The trick here is to know how to anticipate; to know at what speed and
 what distance the subject will pass by.</p>
 <img src="fluffy.jpg" alt="A cat flying by, chasing a ball of yarn, can be
 photographed quite nicely using this technique.">
 <h2>Nature by night</h2>
 <p>To achieve this, you'll need either an extremely sensitive film, or
 immense flash lights.</p>
</article>
<article>
 <h1>About me</h1>
 <h2>My pets</h2>
 <p>I've got a cat named Fluffy and a dog named Miles.</p>
 <img src="fluffy.jpg" alt="Fluffy, my cat, tends to keep itself busy.">
 <p>My dog Miles and I like go on long walks together.</p>
 <h2>music</h2>
 <p>After our walks, having emptied my mind, I like listening to Bach.</p>
</article>
<article>
 <h1>Fluffy and the Yarn</h1>
 <p>Fluffy was a cat who liked to play with yarn. He also liked to jump.</p>
 <aside><img src="fluffy.jpg" alt="" title="Fluffy"></aside>
 <p>He would play in the morning, he would play in the evening.</p>
</article>
3.8.2.1 Requirements for providing text to act as an alternative for images

Status: Last call for comments. ISSUE-31 (missing-alt) blocks progress to Last Call

The requirements for the alt attribute depend on what the image is intended to represent, as described in the following sections.

Status: Last call for comments

When an a element that is a hyperlink, or a button element, has no textual content but contains one or more images, the alt attributes must contain text that together convey the purpose of the link or button.

In this example, a user is asked to pick his preferred color from a list of three. Each color is given by an image, but for users who have configured their user agent not to display images, the color names are used instead:

<h1>Pick your color</h1>
<ul>
 <li><a href="green.html"><img src="green.jpeg" alt="Green"></a></li>
 <li><a href="blue.html"><img src="blue.jpeg" alt="Blue"></a></li>
 <li><a href="red.html"><img src="red.jpeg" alt="Red"></a></li>
</ul>

In this example, each button has a set of images to indicate the kind of color output desired by the user. The first image is used in each case to give the alternative text.

<button name="rgb"><img src="red" alt="RGB"><img src="green" alt=""><img src="blue" alt=""></button>
<button name="cmyk"><img src="cyan" alt="CMYK"><img src="magenta" alt=""><img src="yellow" alt=""><img src="black" alt=""></button>

Since each image represents one part of the text, it could also be written like this:

<button name="rgb"><img src="red" alt="R"><img src="green" alt="G"><img src="blue" alt="B"></button>
<button name="cmyk"><img src="cyan" alt="C"><img src="magenta" alt="M"><img src="yellow" alt="Y"><img src="black" alt="K"></button>

However, with other alternative text, this might not work, and putting all the alternative text into one image in each case might make more sense:

<button name="rgb"><img src="red" alt="sRGB profile"><img src="green" alt=""><img src="blue" alt=""></button>
<button name="cmyk"><img src="cyan" alt="CMYK profile"><img src="magenta" alt=""><img src="yellow" alt=""><img src="black" alt=""></button>
3.8.2.1.2 A phrase or paragraph with an alternative graphical representation: charts, diagrams, graphs, maps, illustrations

Sometimes something can be more clearly stated in graphical form, for example as a flowchart, a diagram, a graph, or a simple map showing directions. In such cases, an image can be given using the img element, but the lesser textual version must still be given, so that users who are unable to view the image (e.g. because they have a very slow connection, or because they are using a text-only browser, or because they are listening to the page being read out by a hands-free automobile voice Web browser, or simply because they are blind) are still able to understand the message being conveyed.

The text must be given in the alt attribute, and must convey the same message as the image specified in the src attribute.

It is important to realize that the alternative text is a replacement for the image, not a description of the image.

In the following example we have a flowchart in image form, with text in the alt attribute rephrasing the flowchart in prose form:

<p>In the common case, the data handled by the tokenization stage
comes from the network, but it can also come from script.</p>
<p><img src="http://dev.w3.org/html5/spec/images/parsing-model-overview.png" alt="The network
passes data to the Tokenizer stage, which passes data to the Tree
Construction stage. From there, data goes to both the DOM and to
Script Execution. Script Execution is linked to the DOM, and, using
document.write(), passes data to the Tokenizer."></p>

Here's another example, showing a good solution and a bad solution to the problem of including an image in a description.

First, here's the good solution. This sample shows how the alternative text should just be what you would have put in the prose if the image had never existed.

<!-- This is the correct way to do things. -->
<p>
 You are standing in an open field west of a house.
 <img src="house.jpeg" alt="The house is white, with a boarded front door.">
 There is a small mailbox here.
</p>

Second, here's the bad solution. In this incorrect way of doing things, the alternative text is simply a description of the image, instead of a textual replacement for the image. It's bad because when the image isn't shown, the text doesn't flow as well as in the first example.

<!-- This is the wrong way to do things. -->
<p>
 You are standing in an open field west of a house.
 <img src="house.jpeg" alt="A white house, with a boarded front door.">
 There is a small mailbox here.
</p>

Text such as "Photo of white house with boarded door" would be equally bad alternative text (though it could be suitable for the title attribute or in the dt element of a figure with this image).

3.8.2.1.3 A short phrase or label with an alternative graphical representation: icons, logos

A document can contain information in iconic form. The icon is intended to help users of visual browsers to recognize features at a glance.

In some cases, the icon is supplemental to a text label conveying the same meaning. In those cases, the alt attribute must be present but must be empty.

Here the icons are next to text that conveys the same meaning, so they have an empty alt attribute:

<nav>
 <p><a href="/help/"><img src="/icons/help.png" alt=""> Help</a></p>
 <p><a href="/configure/"><img src="/icons/configuration.png" alt="">
 Configuration Tools</a></p>
</nav>

In other cases, the icon has no text next to it describing what it means; the icon is supposed to be self-explanatory. In those cases, an equivalent textual label must be given in the alt attribute.

Here, posts on a news site are labeled with an icon indicating their topic.

<body>
 <article>
  <header>
   <h1>Ratatouille wins <i>Best Movie of the Year</i> award</h1>
   <p><img src="movies.png" alt="Movies"></p>
  </header>
  <p>Pixar has won yet another <i>Best Movie of the Year</i> award,
  making this its 8th win in the last 12 years.</p>
 </article>
 <article>
  <header>
   <h1>Latest TWiT episode is online</h1>
   <p><img src="podcasts.png" alt="Podcasts"></p>
  </header>
  <p>The latest TWiT episode has been posted, in which we hear
  several tech news stories as well as learning much more about the
  iPhone. This week, the panelists compare how reflective their
  iPhones' Apple logos are.</p>
 </article>
</body>

Many pages include logos, insignia, flags, or emblems, which stand for a particular entity such as a company, organization, project, band, software package, country, or some such.

If the logo is being used to represent the entity, e.g. as a page heading, the alt attribute must contain the name of the entity being represented by the logo. The alt attribute must not contain text like the word "logo", as it is not the fact that it is a logo that is being conveyed, it's the entity itself.

If the logo is being used next to the name of the entity that it represents, then the logo is supplemental, and its alt attribute must instead be empty.

If the logo is merely used as decorative material (as branding, or, for example, as a side image in an article that mentions the entity to which the logo belongs), then the entry below on purely decorative images applies. If the logo is actually being discussed, then it is being used as a phrase or paragraph (the description of the logo) with an alternative graphical representation (the logo itself), and the first entry above applies.

In the following snippets, all four of the above cases are present. First, we see a logo used to represent a company:

<h1><img src="XYZ.gif" alt="The XYZ company"></h1>

Next, we see a paragraph which uses a logo right next to the company name, and so doesn't have any alternative text:

<article>
 <h2>News</h2>
 <p>We have recently been looking at buying the <img src="alpha.gif"
 alt=""> ΑΒΓ company, a small Greek company
 specializing in our type of product.</p>

In this third snippet, we have a logo being used in an aside, as part of the larger article discussing the acquisition:

 <aside><p><img src="alpha-large.gif" alt=""></p></aside>
 <p>The ΑΒΓ company has had a good quarter, and our
 pie chart studies of their accounts suggest a much bigger blue slice
 than its green and orange slices, which is always a good sign.</p>
</article>

Finally, we have an opinion piece talking about a logo, and the logo is therefore described in detail in the alternative text.

<p>Consider for a moment their logo:</p>

<p><img src="/images/logo" alt="It consists of a green circle with a
green question mark centered inside it."></p>

<p>How unoriginal can you get? I mean, oooooh, a question mark, how
<em>revolutionary</em>, how utterly <em>ground-breaking</em>, I'm
sure everyone will rush to adopt those specifications now! They could
at least have tried for some sort of, I don't know, sequence of
rounded squares with varying shades of green and bold white outlines,
at least that would look good on the cover of a blue book.</p>

This example shows how the alternative text should be written such that if the image isn't available, and the text is used instead, the text flows seamlessly into the surrounding text, as if the image had never been there in the first place.

3.8.2.1.4 Text that has been rendered to a graphic for typographical effect

Status: Last call for comments

Sometimes, an image just consists of text, and the purpose of the image is not to highlight the actual typographic effects used to render the text, but just to convey the text itself.

In such cases, the alt attribute must be present but must consist of the same text as written in the image itself.

Consider a graphic containing the text "Earth Day", but with the letters all decorated with flowers and plants. If the text is merely being used as a heading, to spice up the page for graphical users, then the correct alternative text is just the same text "Earth Day", and no mention need be made of the decorations:

<h1><img src="earthdayheading.png" alt="Earth Day"></h1>
3.8.2.1.5 A graphical representation of some of the surrounding text

Status: Last call for comments

In many cases, the image is actually just supplementary, and its presence merely reinforces the surrounding text. In these cases, the alt attribute must be present but its value must be the empty string.

In general, an image falls into this category if removing the image doesn't make the page any less useful, but including the image makes it a lot easier for users of visual browsers to understand the concept.

A flowchart that repeats the previous paragraph in graphical form:

<p>The network passes data to the Tokenizer stage, which
passes data to the Tree Construction stage. From there, data goes
to both the DOM and to Script Execution. Script Execution is
linked to the DOM, and, using document.write(), passes data to
the Tokenizer.</p>
<p><img src="http://dev.w3.org/html5/spec/images/parsing-model-overview.png" alt=""></p>

In these cases, it would be wrong to include alternative text that consists of just a caption. If a caption is to be included, then either the title attribute can be used, or the figure and dt elements can be used. In the latter case, the image would in fact be a phrase or paragraph with an alternative graphical representation, and would thus require alternative text.

<!-- Using the title="" attribute -->
<p>The network passes data to the Tokenizer stage, which
passes data to the Tree Construction stage. From there, data goes
to both the DOM and to Script Execution. Script Execution is
linked to the DOM, and, using document.write(), passes data to
the Tokenizer.</p>
<p><img src="http://dev.w3.org/html5/spec/images/parsing-model-overview.png" alt=""
        title="Flowchart representation of the parsing model."></p>
<!-- Using <figure> and <dt> -->
<p>The network passes data to the Tokenizer stage, which
passes data to the Tree Construction stage. From there, data goes
to both the DOM and to Script Execution. Script Execution is
linked to the DOM, and, using document.write(), passes data to
the Tokenizer.</p>
<figure>
 <dd>
  <img src="http://dev.w3.org/html5/spec/images/parsing-model-overview.png" alt="The Network leads
  to the Tokenizer, which leads to the Tree Construction. The Tree
  Construction leads to two items. The first is Script Execution, which
  leads via document.write() back to the Tokenizer. The second item
  from which Tree Construction leads is the DOM. The DOM is related to
  the Script Execution.">
 </dd>
 <dt>Flowchart representation of the parsing model.</dt>
</figure>
<!-- This is WRONG. Do not do this. Instead, do what the above examples do. -->
<p>The network passes data to the Tokenizer stage, which
passes data to the Tree Construction stage. From there, data goes
to both the DOM and to Script Execution. Script Execution is
linked to the DOM, and, using document.write(), passes data to
the Tokenizer.</p>
<p><img src="http://dev.w3.org/html5/spec/images/parsing-model-overview.png"
        alt="Flowchart representation of the parsing model."></p>
<!-- Never put the image's caption in the alt="" attribute! -->

A graph that repeats the previous paragraph in graphical form:

<p>According to a study covering several billion pages,
about 62% of documents on the Web in 2007 triggered the Quirks
rendering mode of Web browsers, about 30% triggered the Almost
Standards mode, and about 9% triggered the Standards mode.</p>
<p><img src="rendering-mode-pie-chart.png" alt=""></p>
3.8.2.1.6 A purely decorative image that doesn't add any information

In general, if an image is decorative but isn't especially page-specific, for example an image that forms part of a site-wide design scheme, the image should be specified in the site's CSS, not in the markup of the document.

However, a decorative image that isn't discussed by the surrounding text still has some relevance can be included in a page using the img element. Such images are decorative, but still form part of the content. In these cases, the alt attribute must be present but its value must be the empty string.

Examples where the image is purely decorative despite being relevant would include things like a photo of the Black Rock City landscape in a blog post about an event at Burning Man, or an image of a painting inspired by a poem, on a page reciting that poem. The following snippet shows an example of the latter case (only the first verse is included in this snippet):

<h1>The Lady of Shalott</h1>
<p><img src="shalott.jpeg" alt=""></p>
<p>On either side the river lie<br>
Long fields of barley and of rye,<br>
That clothe the wold and meet the sky;<br>
And through the field the road run by<br>
To many-tower'd Camelot;<br>
And up and down the people go,<br>
Gazing where the lilies blow<br>
Round an island there below,<br>
The island of Shalott.</p>

Status: Last call for comments

When a picture has been sliced into smaller image files that are then displayed together to form the complete picture again, one of the images must have its alt attribute set as per the relevant rules that would be appropriate for the picture as a whole, and then all the remaining images must have their alt attribute set to the empty string.

In the following example, a picture representing a company logo for XYZ Corp has been split into two pieces, the first containing the letters "XYZ" and the second with the word "Corp". The alternative text ("XYZ Corp") is all in the first image.

<h1><img src="logo1.png" alt="XYZ Corp"><img src="logo2.png" alt=""></h1>

In the following example, a rating is shown as three filled stars and two empty stars. While the alternative text could have been "★★★☆☆", the author has instead decided to more helpfully give the rating in the form "3 out of 5". That is the alternative text of the first image, and the rest have blank alternative text.

<p>Rating: <meter max=5 value=3><img src="1" alt="3 out of 5"
  ><img src="1" alt=""><img src="1" alt=""><img src="0" alt=""
  ><img src="0" alt=""></meter></p>

Status: Last call for comments

Generally, image maps should be used instead of slicing an image for links.

However, if an image is indeed sliced and any of the components of the sliced picture are the sole contents of links, then one image per link must have alternative text in its alt attribute representing the purpose of the link.

In the following example, a picture representing the flying spaghetti monster emblem, with each of the left noodly appendages and the right noodly appendages in different images, so that the user can pick the left side or the right side in an adventure.

<h1>The Church</h1>
<p>You come across a flying spaghetti monster. Which side of His
Noodliness do you wish to reach out for?</p>
<p><a href="?go=left" ><img src="fsm-left.png"  alt="Left side. "></a
  ><img src="fsm-middle.png" alt=""
  ><a href="?go=right"><img src="fsm-right.png" alt="Right side."></a></p>
3.8.2.1.9 A key part of the content

Status: Last call for comments

In some cases, the image is a critical part of the content. This could be the case, for instance, on a page that is part of a photo gallery. The image is the whole point of the page containing it.

How to provide alternative text for an image that is a key part of the content depends on the image's provenance.

The general case

When it is possible for detailed alternative text to be provided, for example if the image is part of a series of screenshots in a magazine review, or part of a comic strip, or is a photograph in a blog entry about that photograph, text that can serve as a substitute for the image must be given as the contents of the alt attribute.

A screenshot in a gallery of screenshots for a new OS, with some alternative text:

<figure>
 <dd>
  <img src="KDE%20Light%20desktop.png"
       alt="The desktop is blue, with icons along the left hand side in
            two columns, reading System, Home, K-Mail, etc. A window is
            open showing that menus wrap to a second line if they
            cannot fit in the window. The window has a list of icons
            along the top, with an address bar below it, a list of
            icons for tabs along the left edge, a status bar on the
            bottom, and two panes in the middle. The desktop has a bar
            at the bottom of the screen with a few buttons, a pager, a
            list of open applications, and a clock.">
 </dd>
 <dt>Screenshot of a KDE desktop.</dt>
</figure>

A graph in a financial report:

<img src="sales.gif"
     title="Sales graph"
     alt="From 1998 to 2005, sales increased by the following percentages
     with each year: 624%, 75%, 138%, 40%, 35%, 9%, 21%">

Note that "sales graph" would be inadequate alternative text for a sales graph. Text that would be a good caption is not generally suitable as replacement text.

Images that defy a complete description

In certain cases, the nature of the image might be such that providing thorough alternative text is impractical. For example, the image could be indistinct, or could be a complex fractal, or could be a detailed topographical map.

In these cases, the alt attribute must contain some suitable alternative text, but it may be somewhat brief.

Sometimes there simply is no text that can do justice to an image. For example, there is little that can be said to usefully describe a Rorschach inkblot test. However, a description, even if brief, is still better than nothing:

<figure>
 <dd><img src="/commons/a/a7/Rorschach1.jpg" alt="A shape with left-right
 symmetry with indistinct edges, with a small gap in the center, two
 larger gaps offset slightly from the center, with two similar gaps
 under them. The outline is wider in the top half than the bottom
 half, with the sides extending upwards higher than the center, and
 the center extending below the sides."></dd>
 <dt>A black outline of the first of the ten cards
 in the Rorschach inkblot test.</dt>
</figure>

Note that the following would be a very bad use of alternative text:

<!-- This example is wrong. Do not copy it. -->
<figure>
 <dd><img src="/commons/a/a7/Rorschach1.jpg" alt="A black outline
 of the first of the ten cards in the Rorschach inkblot test."></dd>
 <dt>A black outline of the first of the ten cards
 in the Rorschach inkblot test.</dt>
</figure>

Including the caption in the alternative text like this isn't useful because it effectively duplicates the caption for users who don't have images, taunting them twice yet not helping them any more than if they had only read or heard the caption once.

Another example of an image that defies full description is a fractal, which, by definition, is infinite in detail.

The following example shows one possible way of providing alternative text for the full view of an image of the Mandelbrot set.

<img src="ms1.jpeg" alt="The Mandelbrot set appears as a cardioid with
its cusp on the real axis in the positive direction, with a smaller
bulb aligned along the same center line, touching it in the negative
direction, and with these two shapes being surrounded by smaller bulbs
of various sizes.">
Images whose contents are not known

In some unfortunate cases, there might be no alternative text available at all, either because the image is obtained in some automated fashion without any associated alternative text (e.g. a Webcam), or because the page is being generated by a script using user-provided images where the user did not provide suitable or usable alternative text (e.g. photograph sharing sites), or because the author does not himself know what the images represent (e.g. a blind photographer sharing an image on his blog).

In such cases, the alt attribute's value may be omitted, but one of the following conditions must be met as well:

Such cases are to be kept to an absolute minimum. If there is even the slightest possibility of the author having the ability to provide real alternative text, then it would not be acceptable to omit the alt attribute.

A photo on a photo-sharing site, if the site received the image with no metadata other than the caption:

<figure>
 <dd><img src="1100670787_6a7c664aef.jpg"></dd>
 <dt>Bubbles traveled everywhere with us.</dt>
</figure>

It could also be marked up like this:

<article>
 <h1>Bubbles traveled everywhere with us.</h1>
 <img src="1100670787_6a7c664aef.jpg">
</article>

In either case, though, it would be better if a detailed description of the important parts of the image obtained from the user and included on the page.

A blind user's blog in which a photo taken by the user is shown. Initially, the user might not have any idea what the photo he took shows:

<article>
 <h1>I took a photo</h1>
 <p>I went out today and took a photo!</p>
 <figure>
  <dd><img src="photo2.jpeg"></dd>
  <dt>A photograph taken blindly from my front porch.</dt>
 </figure>
</article>

Eventually though, the user might obtain a description of the image from his friends and could then include alternative text:

<article>
 <h1>I took a photo</h1>
 <p>I went out today and took a photo!</p>
 <figure>
  <dd><img src="photo2.jpeg" alt="The photograph shows my hummingbird
  feeder hanging from the edge of my roof. It is half full, but there
  are no birds around. In the background, out-of-focus trees fill the
  shot. The feeder is made of wood with a metal grate, and it contains
  peanuts. The edge of the roof is wooden too, and is painted white
  with light blue streaks."></dd>
  <dt>A photograph taken blindly from my front porch.</dt>
 </figure>
</article>

Sometimes the entire point of the image is that a textual description is not available, and the user is to provide the description. For instance, the point of a CAPTCHA image is to see if the user can literally read the graphic. Here is one way to mark up a CAPTCHA (note the title attribute):

<p><label>What does this image say?
<img src="captcha.cgi?id=8934" title="CAPTCHA">
<input type=text name=captcha></label>
(If you cannot see the image, you can use an <a
href="?audio">audio</a> test instead.)</p>

Another example would be software that displays images and asks for alternative text precisely for the purpose of then writing a page with correct alternative text. Such a page could have a table of images, like this:

<table>
 <thead>
  <tr> <th> Image <th> Description
 <tbody>
  <tr>
   <td> <img src="2421.png" title="Image 640 by 100, filename 'banner.gif'">
   <td> <input name="alt2421">
  <tr>
   <td> <img src="2422.png" title="Image 200 by 480, filename 'ad3.gif'">
   <td> <input name="alt2422">
</table>

Notice that even in this example, as much useful information as possible is still included in the title attribute.

Since some users cannot use images at all (e.g. because they have a very slow connection, or because they are using a text-only browser, or because they are listening to the page being read out by a hands-free automobile voice Web browser, or simply because they are blind), the alt attribute is only allowed to be omitted rather than being provided with replacement text when no alternative text is available and none can be made available, as in the above examples. Lack of effort from the part of the author is not an acceptable reason for omitting the alt attribute.

3.8.2.1.10 An image not intended for the user

Status: Last call for comments

Generally authors should avoid using img elements for purposes other than showing images.

If an img element is being used for purposes other than showing an image, e.g. as part of a service to count page views, then the alt attribute must be the empty string.

In such cases, the width and height attributes should both be set to zero.

3.8.2.1.11 An image in an e-mail or private document intended for a specific person who is known to be able to view images

Status: Last call for comments

This section does not apply to documents that are publicly accessible, or whose target audience is not necessarily personally known to the author, such as documents on a Web site, e-mails sent to public mailing lists, or software documentation.

When an image is included in a private communication (such as an HTML e-mail) aimed at a specific person who is known to be able to view images, the alt attribute may be omitted. However, even in such cases it is strongly recommended that alternative text be included (as appropriate according to the kind of image involved, as described in the above entries), so that the e-mail is still usable should the user use a mail client that does not support images, or should the document be forwarded on to other users whose abilities might not include easily seeing images.

3.8.2.1.12 General guidelines

Status: Last call for comments

The most general rule to consider when writing alternative text is the following: the intent is that replacing every image with the text of its alt attribute not change the meaning of the page.

So, in general, alternative text can be written by considering what one would have written had one not been able to include the image.

A corollary to this is that the alt attribute's value should never contain text that could be considered the image's caption, title, or legend. It is supposed to contain replacement text that could be used by users instead of the image; it is not meant to supplement the image. The title attribute can be used for supplemental information.

One way to think of alternative text is to think about how you would read the page containing the image to someone over the phone, without mentioning that there is an image present. Whatever you say instead of the image is typically a good start for writing the alternative text.

3.8.2.1.13 Guidance for markup generators

Status: Last call for comments

Markup generators (such as WYSIWYG authoring tools) should, wherever possible, obtain alternative text from their users. However, it is recognized that in many cases, this will not be possible.

For images that are the sole contents of links, markup generators should examine the link target to determine the title of the target, or the URL of the target, and use information obtained in this manner as the alternative text.

As a last resort, implementors should either set the alt attribute to the empty string, under the assumption that the image is a purely decorative image that doesn't add any information but is still specific to the surrounding content, or omit the alt attribute altogether, under the assumption that the image is a key part of the content.

Markup generators should generally avoid using the image's own file name as the alternative text.

3.8.2.1.14 Guidance for conformance checkers

Status: Last call for comments

A conformance checker must report the lack of an alt attribute as an error unless either the conditions listed above for images whose contents are not known apply, or the conformance checker has been configured to assume that the document is an e-mail or document intended for a specific person who is known to be able to view images, or the document has a meta element with a name attribute whose value is an ASCII case-insensitive match for the string "generator".

3.8.3 The iframe element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Embedded content.
Interactive content.
Contexts in which this element may be used:
Where embedded content is expected.
Content model:
Text that conforms to the requirements given in the prose.
Content attributes:
Global attributes
src
name
sandbox
seamless
width
height
DOM interface:
interface HTMLIFrameElement : HTMLElement {
           attribute DOMString src;
           attribute DOMString name;
           attribute DOMString sandbox;
           attribute boolean seamless;
           attribute DOMString width;
           attribute DOMString height;
  readonly attribute Document contentDocument;
  readonly attribute WindowProxy contentWindow;
};

The iframe element represents a nested browsing context.

The src attribute gives the address of a page that the nested browsing context is to contain. The attribute, if present, must be a valid URL. When the browsing context is created, if the attribute is present, the user agent must resolve the value of that attribute, relative to the element, and if that is successful, must then navigate the element's browsing context to the resulting absolute URL, with replacement enabled, and with the iframe element's document's browsing context as the source browsing context. If the user navigates away from this page, the iframe's corresponding WindowProxy object will proxy new Window objects for new Document objects, but the src attribute will not change.

Whenever the src attribute is set, the user agent must resolve the value of that attribute, relative to the element, and if that is successful, the nested browsing context must be navigated to the resulting absolute URL, with the iframe element's document's browsing context as the source browsing context.

If the src attribute is not set when the element is created, or if its value cannot be resolved, the browsing context will remain at the initial about:blank page.

The name attribute, if present, must be a valid browsing context name. The given value is used to name the nested browsing context. When the browsing context is created, if the attribute is present, the browsing context name must be set to the value of this attribute; otherwise, the browsing context name must be set to the empty string.

Whenever the name attribute is set, the nested browsing context's name must be changed to the new value. If the attribute is removed, the browsing context name must be set to the empty string.

When content loads in an iframe, after any load events are fired within the content itself, the user agent must queue a task to fire a simple event named load at the iframe element. When content fails to load (e.g. due to a network error), then the user agent must queue a task to fire a simple event named error at the element instead.

The task source for these tasks is the DOM manipulation task source.

When there is an active parser in the iframe, and when anything in the iframe is delaying the load event of the iframe's browsing context's active document, the iframe must delay the load event of its document.

If, during the handling of the load event, the browsing context in the iframe is again navigated, that will further delay the load event.


The sandbox attribute, when specified, enables a set of extra restrictions on any content hosted by the iframe. Its value must be an unordered set of unique space-separated tokens. The allowed values are allow-same-origin, allow-forms, and allow-scripts. When the attribute is set, the content is treated as being from a unique origin, forms and scripts are disabled, links are prevented from targeting other browsing contexts, and plugins are disabled. The allow-same-origin token allows the content to be treated as being from the same origin instead of forcing it into a unique origin, and the allow-forms and allow-scripts tokens re-enable forms and scripts respectively (though scripts are still prevented from creating popups).

While the sandbox attribute is specified, the iframe element's nested browsing context, and all the browsing contexts nested within it (either directly or indirectly through other nested browsing contexts) must have the following flags set:

The sandboxed navigation browsing context flag

This flag prevents content from navigating browsing contexts other than the sandboxed browsing context itself (or browsing contexts further nested inside it).

This flag also prevents content from creating new auxiliary browsing contexts, e.g. using the target attribute or the window.open() method.

The sandboxed plugins browsing context flag

This flag prevents content from instantiating plugins, whether using the embed element, the object element, the applet element, or through navigation of a nested browsing context.

The sandboxed seamless iframes flag

This flag prevents content from using the seamless attribute on descendant iframe elements.

This prevents a page inserted using the allow-same-origin keyword from using a CSS-selector-based method of probing the DOM of other pages on the same site (in particular, pages that contain user-sensitive information).

The sandboxed origin browsing context flag, unless the sandbox attribute's value, when split on spaces, is found to have the allow-same-origin keyword set

This flag forces content into a unique origin for the purposes of the same-origin policy.

This flag also prevents script from reading the document.cookie IDL attribute.

The allow-same-origin attribute is intended for two cases.

First, it can be used to allow content from the same site to be sandboxed to disable scripting, while still allowing access to the DOM of the sandboxed content.

Second, it can be used to embed content from a third-party site, sandboxed to prevent that site from opening popup windows, etc, without preventing the embedded page from communicating back to its originating site, using the database APIs to store data, etc.

This flag only takes effect when the nested browsing context of the iframe is navigated.

The sandboxed forms browsing context flag, unless the sandbox attribute's value, when split on spaces, is found to have the allow-forms keyword set

This flag blocks form submission.

The sandboxed scripts browsing context flag, unless the sandbox attribute's value, when split on spaces, is found to have the allow-scripts keyword set

This flag blocks script execution.

If the sandbox attribute is dynamically added after the iframe has loaded a page, scripts already compiled by that page (whether in script elements, or in event handlers, or elsewhere) will continue to run. Only new scripts will be prevented from executing by this flag.

These flags must not be set unless the conditions listed above define them as being set.

In this example, some completely-unknown, potentially hostile, user-provided HTML content is embedded in a page. Because it is sandboxed, it is treated by the user agent as being from a unique origin, despite the content being served from the same site. Thus it is affected by all the normal cross-site restrictions. In addition, the embedded page has scripting disabled, plugins disabled, forms disabled, and it cannot navigate any frames or windows other than itself (or any frames or windows it itself embeds).

<p>We're not scared of you! Here is your content, unedited:</p>
<iframe sandbox src="getusercontent.cgi?id=12193"></iframe>

Note that cookies are still sent to the server in the getusercontent.cgi request, though they are not visible in the document.cookie IDL attribute.

In this example, a gadget from another site is embedded. The gadget has scripting and forms enabled, and the origin sandbox restrictions are lifted, allowing the gadget to communicate with its originating server. The sandbox is still useful, however, as it disables plugins and popups, thus reducing the risk of the user being exposed to malware and other annoyances.

<iframe sandbox="allow-same-origin allow-forms allow-scripts"
        src="http://maps.example.com/embedded.html"></iframe>

The seamless attribute is a boolean attribute. When specified, it indicates that the iframe element's browsing context is to be rendered in a manner that makes it appear to be part of the containing document (seamlessly included in the parent document). Specifically, when the attribute is set on an iframe element whose owner Document's browsing context does not have the sandboxed seamless iframes flag set and while either the browsing context's active document has the same origin as the iframe element's document, or the browsing context's active document's address has the same origin as the iframe element's document, the following requirements apply:

If the attribute is not specified, or if the origin conditions listed above are not met, then the user agent should render the nested browsing context in a manner that is clearly distinguishable as a separate browsing context, and the seamless browsing context flag must be set to false for that browsing context.

It is important that user agents recheck the above conditions whenever the active document of the nested browsing context of the iframe changes, such that the seamless browsing context flag gets unset if the nested browsing context is navigated to another origin.

The attribute can be set or removed dynamically, with the rendering updating in tandem.

In this example, the site's navigation is embedded using a client-side include using an iframe. Any links in the iframe will, in new user agents, be automatically opened in the iframe's parent browsing context; for legacy user agents, the site could also include a base element with a target attribute with the value _parent. Similarly, in new user agents the styles of the parent page will be automatically applied to the contents of the frame, but to support legacy user agents authors might wish to include the styles explicitly.

<nav><iframe seamless src="nav.include.html"></iframe></nav>

The iframe element supports dimension attributes for cases where the embedded content has specific dimensions (e.g. ad units have well-defined dimensions).

An iframe element never has fallback content, as it will always create a nested browsing context, regardless of whether the specified initial contents are successfully used.

Descendants of iframe elements represent nothing. (In legacy user agents that do not support iframe elements, the contents would be parsed as markup that could act as fallback content.)

When used in HTML documents, the allowed content model of iframe elements is text, except that invoking the HTML fragment parsing algorithm with the iframe element as the context element and the text contents as the input must result in a list of nodes that are all phrasing content, with no parse errors having occurred, with no script elements being anywhere in the list or as descendants of elements in the list, and with all the elements in the list (including their descendants) being themselves conforming.

The iframe element must be empty in XML documents.

The HTML parser treats markup inside iframe elements as text.

The IDL attributes src, name, sandbox, and seamless must reflect the respective content attributes of the same name.

The contentDocument IDL attribute must return the Document object of the active document of the iframe element's nested browsing context.

The contentWindow IDL attribute must return the WindowProxy object of the iframe element's nested browsing context.

Here is an example of a page using an iframe to include advertising from an advertising broker:

<iframe src="http://ads.example.com/?customerid=923513721&amp;format=banner"
        width="468" height="60"></iframe>

3.8.4 The embed element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Embedded content.
Interactive content.
Contexts in which this element may be used:
Where embedded content is expected.
Content model:
Empty.
Content attributes:
Global attributes
src
type
width
height
Any other attribute that has no namespace (see prose).
DOM interface:
interface HTMLEmbedElement : HTMLElement {
           attribute DOMString src;
           attribute DOMString type;
           attribute DOMString width;
           attribute DOMString height;
};

Depending on the type of content instantiated by the embed element, the node may also support other interfaces.

The embed element represents an integration point for an external (typically non-HTML) application or interactive content.

The src attribute gives the address of the resource being embedded. The attribute, if present, must contain a valid URL.

The type attribute, if present, gives the MIME type of the plugin to instantiate. The value must be a valid MIME type, optionally with parameters. If both the type attribute and the src attribute are present, then the type attribute must specify the same type as the explicit Content-Type metadata of the resource given by the src attribute.

When the element is created with neither a src attribute nor a type attribute, and when attributes are removed such that neither attribute is present on the element anymore, and when the element has a media element ancestor, and when the element has an ancestor object element that is not showing its fallback content, any plugins instantiated for the element must be removed, and the embed element represents nothing.

When the sandboxed plugins browsing context flag is set on the browsing context for which the embed element's document is the active document, then the user agent must render the embed element in a manner that conveys that the plugin was disabled. The user agent may offer the user the option to override the sandbox and instantiate the plugin anyway; if the user invokes such an option, the user agent must act as if the sandboxed plugins browsing context flag was not set for the purposes of this element.

Plugins are disabled in sandboxed browsing contexts because they might not honor the restrictions imposed by the sandbox (e.g. they might allow scripting even when scripting in the sandbox is disabled). User agents should convey the danger of overriding the sandbox to the user if an option to do so is provided.

An embed element is said to be potentially active when the following conditions are all met simultaneously:

Whenever an embed element that was not potentially active becomes potentially active, and whenever a potentially active embed element's src attribute is set, changed, or removed, and whenever a potentially active embed element's type attribute is set, changed, or removed, the appropriate set of steps from the following is then applied:

If the element has a src attribute set

The user agent must resolve the value of the element's src attribute, relative to the element. If that is successful, the user agent should fetch the resulting absolute URL, from the element's browsing context scope origin if it has one. The task that is queued by the networking task source once the resource has been fetched must find and instantiate an appropriate plugin based on the content's type, and hand that plugin the content of the resource, replacing any previously instantiated plugin for the element.

Fetching the resource must delay the load event of the element's document.

If the element has no src attribute set

The user agent should find and instantiate an appropriate plugin based on the value of the type attribute.

Whenever an embed element that was potentially active stops being potentially active, any plugin that had been instantiated for that element must be unloaded.

The embed element is unaffected by the CSS 'display' property. The selected plugin is instantiated even if the element is hidden with a 'display:none' CSS style.

The type of the content being embedded is defined as follows:

  1. If the element has a type attribute, and that attribute's value is a type that a plugin supports, then the value of the type attribute is the content's type.

  2. Otherwise, if the <path> component of the URL of the specified resource (after any redirects) matches a pattern that a plugin supports, then the content's type is the type that that plugin can handle.

    For example, a plugin might say that it can handle resources with <path> components that end with the four character string ".swf".

  3. Otherwise, if the specified resource has explicit Content-Type metadata, then that is the content's type.

  4. Otherwise, the content has no type and there can be no appropriate plugin for it.

The embed element has no fallback content. If the user agent can't find a suitable plugin, then the user agent must use a default plugin. (This default could be as simple as saying "Unsupported Format".)

Whether the resource is fetched successfully or not (e.g. whether the response code was a 2xx code or equivalent) must be ignored when determining the resource's type and when handing the resource to the plugin.

This allows servers to return data for plugins even with error responses (e.g. HTTP 500 Internal Server Error codes can still contain plugin data).

Any namespace-less attribute other than name and align may be specified on the embed element, so long as its name is XML-compatible and contains no characters in the range U+0041 to U+005A (LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z). These attributes are then passed as parameters to the plugin.

All attributes in HTML documents get lowercased automatically, so the restriction on uppercase letters doesn't affect such documents.

The two exceptions are to exclude legacy attributes that have side-effects beyond just sending parameters to the plugin.

The user agent should pass the names and values of all the attributes of the embed element that have no namespace to the plugin used, when it is instantiated.

If the plugin instantiated for the embed element supports a scriptable interface, the HTMLEmbedElement object representing the element should expose that interface while the element is instantiated.

The embed element supports dimension attributes.

The IDL attributes src and type each must reflect the respective content attributes of the same name.

Here's a way to embed a resource that requires a proprietary plug-in, like Flash:

<embed src="catgame.swf">

If the user does not have the plug-in (for example if the plug-in vendor doesn't support the user's platform), then the user will be unable to use the resource.

To pass the plugin a parameter "quality" with the value "high", an attribute can be specified:

<embed src="catgame.swf" quality="high">

This would be equivalent to the following, when using an object element instead:

<object data="catgame.swf">
 <param name="quality" value="high">
</object>

3.8.5 The object element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Embedded content.
If the element has a usemap attribute: Interactive content.
Listed, submittable, form-associated element.
Contexts in which this element may be used:
Where embedded content is expected.
Content model:
Zero or more param elements, then, transparent.
Content attributes:
Global attributes
data
type
name
usemap
form
width
height
DOM interface:
interface HTMLObjectElement : HTMLElement {
           attribute DOMString data;
           attribute DOMString type;
           attribute DOMString name;
           attribute DOMString useMap;
  readonly attribute HTMLFormElement form;
           attribute DOMString width;
           attribute DOMString height;
  readonly attribute Document contentDocument;
  readonly attribute WindowProxy contentWindow;

  readonly attribute boolean willValidate;
  readonly attribute ValidityState validity;
  readonly attribute DOMString validationMessage;
  boolean checkValidity();
  void setCustomValidity(in DOMString error);
};

Depending on the type of content instantiated by the object element, the node also supports other interfaces.

The object element can represent an external resource, which, depending on the type of the resource, will either be treated as an image, as a nested browsing context, or as an external resource to be processed by a plugin.

The data attribute, if present, specifies the address of the resource. If present, the attribute must be a valid URL.

The type attribute, if present, specifies the type of the resource. If present, the attribute must be a valid MIME type, optionally with parameters.

At least one of either the data attribute or the type attribute must be present.

The name attribute, if present, must be a valid browsing context name. The given value is used to name the nested browsing context, if applicable.

When the element is created, and subsequently whenever the element is inserted into a document or removed from a document; and whenever the element's Document changes whether it is fully active; and whenever an ancestor object element changes to or from showing its fallback content; and whenever the element's classid attribute is set, changed, or removed; and, when its classid attribute is not present, whenever its data attribute is set, changed, or removed; and, when neither its classid attribute nor its data attribute are present, whenever its type attribute is set, changed, or removed: the user agent must queue a task to run the following steps to (re)determine what the object element represents:

  1. If the user has indicated a preference that this object element's fallback content be shown instead of the element's usual behavior, then jump to the last step in the overall set of steps (fallback).

    For example, a user could ask for the element's fallback content to be shown because that content uses a format that the user finds more accessible.

  2. If the element has an ancestor media element, or has an ancestor object element that is not showing its fallback content, or if the element is not in a Document, or if the element's Document is not fully active, then jump to the last step in the overall set of steps (fallback).

  3. If the classid attribute is present, and has a value that isn't the empty string, then: if the user agent can find a plugin suitable according to the value of the classid attribute, and plugins aren't being sandboxed, then that plugin should be used, and the value of the data attribute, if any, should be passed to the plugin. If no suitable plugin can be found, or if the plugin reports an error, jump to the last step in the overall set of steps (fallback).

  4. If the data attribute is present, then:

    1. If the type attribute is present and its value is not a type that the user agent supports, and is not a type that the user agent can find a plugin for, then the user agent may jump to the last step in the overall set of steps (fallback) without fetching the content to examine its real type.

    2. Resolve the URL specified by the data attribute, relative to the element.

      If that is successful, fetch the resulting absolute URL, from the element's browsing context scope origin if it has one.

      Fetching the resource must delay the load event of the element's document until the task that is queued by the networking task source once the resource has been fetched (defined next) has been run.

    3. If the resource is not yet available (e.g. because the resource was not available in the cache, so that loading the resource required making a request over the network), then jump to the last step in the overall set of steps (fallback). The task that is queued by the networking task source once the resource is available must restart this algorithm from this step. Resources can load incrementally; user agents may opt to consider a resource "available" whenever enough data has been obtained to begin processing the resource.

    4. If the load failed (e.g. the URL could not be resolved, there was an HTTP 404 error, there was a DNS error), fire a simple event named error at the element, then jump to the last step in the overall set of steps (fallback).

    5. Determine the resource type, as follows:

      1. Let the resource type be unknown.

      2. Let the sniffed flag be false.

      3. If there is a type attribute present on the object element, and that attribute's value is not a type that the user agent supports, but it is a type that a plugin supports, then let the resource type be the type specified in that type attribute.

      4. Otherwise, if the resource type is unknown, and the resource has associated Content-Type metadata, then let the resource type be the type specified in the resource's Content-Type metadata.

        If this results in the resource type being "text/plain", then let the resource type be the result of applying the rules for distingushing if a resource is text or binary to the resource instead, and then set the sniffed flag to true.

      5. If the resource type is unknown or "application/octet-stream" at this point and there is a type attribute present on the object element, then change the resource type to instead be the type specified in that type attribute.

        Otherwise, if the resource type is "application/octet-stream" but there is no type attribute on the object element, then change the resource type to be unknown, so that the sniffing rules in the following steps are invoked.

      6. If the resource type is still unknown at this point, but the <path> component of the URL of the specified resource (after any redirects) matches a pattern that a plugin supports, then let resource type be the type that that plugin can handle.

        For example, a plugin might say that it can handle resources with <path> components that end with the four character string ".swf".

      7. If the resource type is still unknown, and the sniffed flag is false, then change the resource type to instead be the sniffed type of the resource.

        Otherwise, if the resource type is still unknown, and the sniffed flag is true, then change the resource type back to text/plain.

    6. Handle the content as given by the first of the following cases that matches:

      If the resource type is not a type that the user agent supports, but it is a type that a plugin supports

      If plugins are being sandboxed, jump to the last step in the overall set of steps (fallback).

      Otherwise, the user agent should use the plugin that supports resource type and pass the content of the resource to that plugin. If the plugin reports an error, then jump to the last step in the overall set of steps (fallback).

      If the resource type is an XML MIME type, or if the resource type does not start with "image/"

      The object element must be associated with a nested browsing context, if it does not already have one. The element's nested browsing context must then be navigated to the given resource, with replacement enabled, and with the object element's document's browsing context as the source browsing context. (The data attribute of the object element doesn't get updated if the browsing context gets further navigated to other locations.)

      The object element represents the nested browsing context.

      If the name attribute is present, the browsing context name must be set to the value of this attribute; otherwise, the browsing context name must be set to the empty string.

      It's possible that the navigation of the browsing context will actually obtain the resource from a different application cache. Even if the resource is then found to have a different type, it is still used as part of a nested browsing context; this algorithm doesn't restart with the new resource.

      If the resource type starts with "image/", and support for images has not been disabled

      Apply the image sniffing rules to determine the type of the image.

      The object element represents the specified image. The image is not a nested browsing context.

      If the image cannot be rendered, e.g. because it is malformed or in an unsupported format, jump to the last step in the overall set of steps (fallback).

      Otherwise

      The given resource type is not supported. Jump to the last step in the overall set of steps (fallback).

    7. The element's contents are not part of what the object element represents.

    8. Once the resource is completely loaded, queue a task to fire a simple event named load at the element.

      The task source for this task is the DOM manipulation task source.

  5. If the data attribute is absent but the type attribute is present, plugins aren't being sandboxed, and the user agent can find a plugin suitable according to the value of the type attribute, then that plugin should be used. If no suitable plugin can be found, or if the plugin reports an error, jump to the next step (fallback).

  6. (Fallback.) The object element represents the element's children, ignoring any leading param element children. This is the element's fallback content. If the element has an instantiated plugin, then unload it.

The task source for the task above is the DOM manipulation task source.

When the algorithm above instantiates a plugin, the user agent should pass the names and values of all the attributes on the element, and all the names and values of parameters given by param elements that are children of the object element, in tree order, to the plugin used. If the plugin supports a scriptable interface, the HTMLObjectElement object representing the element should expose that interface. The object element represents the plugin. The plugin is not a nested browsing context.

If the sandboxed plugins browsing context flag is set on the browsing context for which the object element's document is the active document, then the steps above must always act as if they had failed to find a plugin, even if one would otherwise have been used.

The above algorithm is independent of CSS properties (including 'display', 'overflow', and 'visibility'). For example, it runs even if the element is hidden with a 'display:none' CSS style, and does not run again if the element's visibility changes.

Due to the algorithm above, the contents of object elements act as fallback content, used only when referenced resources can't be shown (e.g. because it returned a 404 error). This allows multiple object elements to be nested inside each other, targeting multiple user agents with different capabilities, with the user agent picking the first one it supports.

Whenever the name attribute is set, if the object element has a nested browsing context, its name must be changed to the new value. If the attribute is removed, if the object element has a browsing context, the browsing context name must be set to the empty string.

The usemap attribute, if present while the object element represents an image, can indicate that the object has an associated image map. The attribute must be ignored if the object element doesn't represent an image.

The form attribute is used to explicitly associate the object element with its form owner.

Constraint validation: object elements are always barred from constraint validation.

The object element supports dimension attributes.

The IDL attributes data, type, name, and useMap each must reflect the respective content attributes of the same name.

The contentDocument IDL attribute must return the Document object of the active document of the object element's nested browsing context, if it has one; otherwise, it must return null.

The contentWindow IDL attribute must return the WindowProxy object of the object element's nested browsing context, if it has one; otherwise, it must return null.

The willValidate, validity, and validationMessage attributes, and the checkValidity() and setCustomValidity() methods, are part of the constraint validation API.

In the following example, a Java applet is embedded in a page using the object element. (Generally speaking, it is better to avoid using applets like these and instead use native JavaScript and HTML to provide the functionality, since that way the application will work on all Web browsers without requiring a third-party plugin. Many devices, especially embedded devices, do not support third-party technologies like Java.)

<figure>
 <dd>
  <object type="application/x-java-applet">
   <param name="code" value="MyJavaClass">
   <p>You do not have Java available, or it is disabled.</p>
  </object>
 </dd>
 <dt>My Java Clock</dt>
</figure>

In this example, an HTML page is embedded in another using the object element.

<figure>
 <dd><object data="clock.html"></object>
 <dt>My HTML Clock
</figure>

3.8.6 The param element

Status: Last call for comments

Categories
None.
Contexts in which this element may be used:
As a child of an object element, before any flow content.
Content model:
Empty.
Content attributes:
Global attributes
name
value
DOM interface:
interface HTMLParamElement : HTMLElement {
           attribute DOMString name;
           attribute DOMString value;
};

The param element defines parameters for plugins invoked by object elements. It does not represent anything on its own.

The name attribute gives the name of the parameter.

The value attribute gives the value of the parameter.

Both attributes must be present. They may have any value.

If both attributes are present, and if the parent element of the param is an object element, then the element defines a parameter with the given name/value pair.

The IDL attributes name and value must both reflect the respective content attributes of the same name.

The following example shows how the param element can be used to pass a parameter to a plugin, in this case the Flash plugin.

<!DOCTYPE HTML>
<html lang="en">
 <head>
  <title>Flash test page</title>
 </head>
 <body>
  <p>
   <object type="application/x-shockwave-flash">
    <param name=movie value="http://www.macromedia.com/shockwave/download/triggerpages_mmcom/flash.swf">
    This page requires the use of a proprietary technology. Since you
    have not installed the software product required to view this
    page, you should try visiting another site that instead uses open
    vendor-neutral technologies.
   </object> 
  </p>
 </body>
</html>

3.8.7 The video element

Status: Last call for comments. ISSUE-9 (video-accessibility) blocks progress to Last Call

Categories
Flow content.
Phrasing content.
Embedded content.
If the element has a controls attribute: Interactive content.
Contexts in which this element may be used:
Where embedded content is expected.
Content model:
If the element has a src attribute: transparent, but with no media element descendants.
If the element does not have a src attribute: one or more source elements, then, transparent, but with no media element descendants.
Content attributes:
Global attributes
src
poster
autobuffer
autoplay
loop
controls
width
height
DOM interface:
interface HTMLVideoElement : HTMLMediaElement {
           attribute DOMString width;
           attribute DOMString height;
  readonly attribute unsigned long videoWidth;
  readonly attribute unsigned long videoHeight;
           attribute DOMString poster;
};

A video element is used for playing videos or movies.

Content may be provided inside the video element. User agents should not show this content to the user; it is intended for older Web browsers which do not support video, so that legacy video plugins can be tried, or to show text to the users of these older browsers informing them of how to access the video contents.

In particular, this content is not intended to address accessibility concerns. To make video content accessible to the blind, deaf, and those with other physical or cognitive disabilities, authors are expected to provide alternative media streams and/or to embed accessibility aids (such as caption or subtitle tracks, audio description tracks, or sign-language overlays) into their media streams.

The video element is a media element whose media data is ostensibly video data, possibly with associated audio data.

The src, autobuffer, autoplay, loop, and controls attributes are the attributes common to all media elements.

The poster attribute gives the address of an image file that the user agent can show while no video data is available. The attribute, if present, must contain a valid URL. If the specified resource is to be used, then, when the element is created or when the poster attribute is set, its value must be resolved relative to the element, and if that is successful, the resulting absolute URL must be fetched, from the element's Document's origin; this must delay the load event of the element's document. The poster frame is then the image obtained from that resource, if any.

The image given by the poster attribute, the poster frame, is intended to be a representative frame of the video (typically one of the first non-blank frames) that gives the user an idea of what the video is like.

The poster IDL attribute must reflect the poster content attribute.


When no video data is available (the element's readyState attribute is either HAVE_NOTHING, or HAVE_METADATA but no video data has yet been obtained at all), the video element represents either the poster frame, or nothing.

When a video element is paused and the current playback position is the first frame of video, the element represents either the frame of video corresponding to the current playback position or the poster frame, at the discretion of the user agent.

Notwithstanding the above, the poster frame should be preferred over nothing, but the poster frame should not be shown again after a frame of video has been shown.

When a video element is paused at any other position, the element represents the frame of video corresponding to the current playback position, or, if that is not yet available (e.g. because the video is seeking or buffering), the last frame of the video to have been rendered.

When a video element is potentially playing, it represents the frame of video at the continuously increasing "current" position. When the current playback position changes such that the last frame rendered is no longer the frame corresponding to the current playback position in the video, the new frame must be rendered. Similarly, any audio associated with the video must, if played, be played synchronized with the current playback position, at the specified volume with the specified mute state.

When a video element is neither potentially playing nor paused (e.g. when seeking or stalled), the element represents the last frame of the video to have been rendered.

Which frame in a video stream corresponds to a particular playback position is defined by the video stream's format.

In addition to the above, the user agent may provide messages to the user (such as "buffering", "no video loaded", "error", or more detailed information) by overlaying text or icons on the video or other areas of the element's playback area, or in another appropriate manner.

User agents that cannot render the video may instead make the element represent a link to an external video playback utility or to the video data itself.


video . videoWidth
video . videoHeight

These attributes return the intrinsic dimensions of the video, or zero if the dimensions are not known.

The intrinsic width and intrinsic height of the media resource are the dimensions of the resource in CSS pixels after taking into account the resource's dimensions, aspect ratio, clean aperture, resolution, and so forth, as defined for the format used by the resource. If an anamorphic format does not define how to apply the aspect ratio to the video data's dimensions to obtain the "correct" dimensions, then the user agent must apply the ratio by increasing one dimension and leaving the other unchanged.

The videoWidth IDL attribute must return the intrinsic width of the video in CSS pixels. The videoHeight IDL attribute must return the intrinsic height of the video in CSS pixels. If the element's readyState attribute is HAVE_NOTHING, then the attributes must return 0.

The video element supports dimension attributes.

Video content should be rendered inside the element's playback area such that the video content is shown centered in the playback area at the largest possible size that fits completely within it, with the video content's aspect ratio being preserved. Thus, if the aspect ratio of the playback area does not match the aspect ratio of the video, the video will be shown letterboxed or pillarboxed. Areas of the element's playback area that do not contain the video represent nothing.

The intrinsic width of a video element's playback area is the intrinsic width of the video resource, if that is available; otherwise it is the intrinsic width of the poster frame, if that is available; otherwise it is 300 CSS pixels.

The intrinsic height of a video element's playback area is the intrinsic height of the video resource, if that is available; otherwise it is the intrinsic height of the poster frame, if that is available; otherwise it is 150 CSS pixels.


User agents should provide controls to enable or disable the display of closed captions, audio description tracks, and other additional data associated with the video stream, though such features should, again, not interfere with the page's normal rendering.

User agents may allow users to view the video content in manners more suitable to the user (e.g. full-screen or in an independent resizable window). As for the other user interface features, controls to enable this should not interfere with the page's normal rendering unless the user agent is exposing a user interface. In such an independent context, however, user agents may make full user interfaces visible, with, e.g., play, pause, seeking, and volume controls, even if the controls attribute is absent.

User agents may allow video playback to affect system features that could interfere with the user's experience; for example, user agents could disable screensavers while video playback is in progress.

User agents should not provide a public API to cause videos to be shown full-screen. A script, combined with a carefully crafted video file, could trick the user into thinking a system-modal dialog had been shown, and prompt the user for a password. There is also the danger of "mere" annoyance, with pages launching full-screen videos when links are clicked or pages navigated. Instead, user-agent-specific interface features may be provided to easily allow the user to obtain a full-screen playback mode.

3.8.8 The audio element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Embedded content.
If the element has a controls attribute: Interactive content.
Contexts in which this element may be used:
Where embedded content is expected.
Content model:
If the element has a src attribute: transparent, but with no media element descendants.
If the element does not have a src attribute: one or more source elements, then, transparent, but with no media element descendants.
Content attributes:
Global attributes
src
autobuffer
autoplay
loop
controls
DOM interface:
[NamedConstructor=Audio(),
 NamedConstructor=Audio(in DOMString src)]
interface HTMLAudioElement : HTMLMediaElement {};

An audio element represents a sound or audio stream.

Content may be provided inside the audio element. User agents should not show this content to the user; it is intended for older Web browsers which do not support audio, so that legacy audio plugins can be tried, or to show text to the users of these older browsers informing them of how to access the audio contents.

In particular, this content is not intended to address accessibility concerns. To make audio content accessible to the deaf or to those with other physical or cognitive disabilities, authors are expected to provide alternative media streams and/or to embed accessibility aids (such as transcriptions) into their media streams.

The audio element is a media element whose media data is ostensibly audio data.

The src, autobuffer, autoplay, loop, and controls attributes are the attributes common to all media elements.

When an audio element is potentially playing, it must have its audio data played synchronized with the current playback position, at the specified volume with the specified mute state.

When an audio element is not potentially playing, audio must not play for the element.

audio = new Audio( [ url ] )

Returns a new audio element, with the src attribute set to the value passed in the argument, if applicable.

Two constructors are provided for creating HTMLAudioElement objects (in addition to the factory methods from DOM Core such as createElement()): Audio() and Audio(src). When invoked as constructors, these must return a new HTMLAudioElement object (a new audio element). The element must have its autobuffer attribute set to the literal value "autobuffer". If the src argument is present, the object created must have its src content attribute set to the provided value, and the user agent must invoke the object's resource selection algorithm before returning. The element's document must be the active document of the browsing context of the Window object on which the interface object of the invoked constructor is found.

3.8.9 The source element

Status: Last call for comments

Categories
None.
Contexts in which this element may be used:
As a child of a media element, before any flow content.
Content model:
Empty.
Content attributes:
Global attributes
src
type
media
DOM interface:
interface HTMLSourceElement : HTMLElement {
           attribute DOMString src;
           attribute DOMString type;
           attribute DOMString media;
};

The source element allows authors to specify multiple alternative media resources for media elements. It does not represent anything on its own.

The src attribute gives the address of the media resource. The value must be a valid URL. This attribute must be present.

The type attribute gives the type of the media resource, to help the user agent determine if it can play this media resource before fetching it. If specified, its value must be a valid MIME type. The codecs parameter may be specified and might be necessary to specify exactly how the resource is encoded. [RFC4281]

The following list shows some examples of how to use the codecs= MIME parameter in the type attribute.

H.264 Simple baseline profile video (main and extended video compatible) level 3 and Low-Complexity AAC audio in MP4 container
<source src='video.mp4' type='video/mp4; codecs="avc1.42E01E, mp4a.40.2"'>
H.264 Extended profile video (baseline-compatible) level 3 and Low-Complexity AAC audio in MP4 container
<source src='video.mp4' type='video/mp4; codecs="avc1.58A01E, mp4a.40.2"'>
H.264 Main profile video level 3 and Low-Complexity AAC audio in MP4 container
<source src='video.mp4' type='video/mp4; codecs="avc1.4D401E, mp4a.40.2"'>
H.264 'High' profile video (incompatible with main, baseline, or extended profiles) level 3 and Low-Complexity AAC audio in MP4 container
<source src='video.mp4' type='video/mp4; codecs="avc1.64001E, mp4a.40.2"'>
MPEG-4 Visual Simple Profile Level 0 video and Low-Complexity AAC audio in MP4 container
<source src='video.mp4' type='video/mp4; codecs="mp4v.20.8, mp4a.40.2"'>
MPEG-4 Advanced Simple Profile Level 0 video and Low-Complexity AAC audio in MP4 container
<source src='video.mp4' type='video/mp4; codecs="mp4v.20.240, mp4a.40.2"'>
MPEG-4 Visual Simple Profile Level 0 video and AMR audio in 3GPP container
<source src='video.3gp' type='video/3gpp; codecs="mp4v.20.8, samr"'>
Theora video and Vorbis audio in Ogg container
<source src='video.ogv' type='video/ogg; codecs="theora, vorbis"'>
Theora video and Speex audio in Ogg container
<source src='video.ogv' type='video/ogg; codecs="theora, speex"'>
Vorbis audio alone in Ogg container
<source src='audio.ogg' type='audio/ogg; codecs=vorbis'>
Speex audio alone in Ogg container
<source src='audio.spx' type='audio/ogg; codecs=speex'>
FLAC audio alone in Ogg container
<source src='audio.oga' type='audio/ogg; codecs=flac'>
Dirac video and Vorbis audio in Ogg container
<source src='video.ogv' type='video/ogg; codecs="dirac, vorbis"'>
Theora video and Vorbis audio in Matroska container
<source src='video.mkv' type='video/x-matroska; codecs="theora, vorbis"'>

The media attribute gives the intended media type of the media resource, to help the user agent determine if this media resource is useful to the user before fetching it. Its value must be a valid media query.

The default, if the media attribute is omitted, is "all", meaning that by default the media resource is suitable for all media.

If a source element is inserted as a child of a media element that has no src attribute and whose networkState has the value NETWORK_EMPTY, the user agent must invoke the media element's resource selection algorithm.

The IDL attributes src, type, and media must reflect the respective content attributes of the same name.

3.8.10 Media elements

Status: Last call for comments

Media elements implement the following interface:

interface HTMLMediaElement : HTMLElement {

  // error state
  readonly attribute MediaError error;

  // network state
           attribute DOMString src;
  readonly attribute DOMString currentSrc;
  const unsigned short NETWORK_EMPTY = 0;
  const unsigned short NETWORK_IDLE = 1;
  const unsigned short NETWORK_LOADING = 2;
  const unsigned short NETWORK_NO_SOURCE = 3;
  readonly attribute unsigned short networkState;
           attribute boolean autobuffer;
  readonly attribute TimeRanges buffered;
  void load();
  DOMString canPlayType(in DOMString type);

  // ready state
  const unsigned short HAVE_NOTHING = 0;
  const unsigned short HAVE_METADATA = 1;
  const unsigned short HAVE_CURRENT_DATA = 2;
  const unsigned short HAVE_FUTURE_DATA = 3;
  const unsigned short HAVE_ENOUGH_DATA = 4;
  readonly attribute unsigned short readyState;
  readonly attribute boolean seeking;

  // playback state
           attribute float currentTime;
  readonly attribute float startTime;
  readonly attribute float duration;
  readonly attribute boolean paused;
           attribute float defaultPlaybackRate;
           attribute float playbackRate;
  readonly attribute TimeRanges played;
  readonly attribute TimeRanges seekable;
  readonly attribute boolean ended;
           attribute boolean autoplay;
           attribute boolean loop;
  void play();
  void pause();



  // controls
           attribute boolean controls;
           attribute float volume;
           attribute boolean muted;
};

The media element attributes, src, autobuffer, autoplay, loop, and controls, apply to all media elements. They are defined in this section.

Media elements are used to present audio data, or video and audio data, to the user. This is referred to as media data in this section, since this section applies equally to media elements for audio or for video. The term media resource is used to refer to the complete set of media data, e.g. the complete video file, or complete audio file.

Except where otherwise specified, the task source for all the tasks queued in this section and its subsections is the media element event task source.

3.8.10.1 Error codes

Status: Last call for comments

media . error

Returns a MediaError object representing the current error state of the element.

Returns null if there is no error.

All media elements have an associated error status, which records the last error the element encountered since its resource selection algorithm was last invoked. The error attribute, on getting, must return the MediaError object created for this last error, or null if there has not been an error.

interface MediaError {
  const unsigned short MEDIA_ERR_ABORTED = 1;
  const unsigned short MEDIA_ERR_NETWORK = 2;
  const unsigned short MEDIA_ERR_DECODE = 3;
  const unsigned short MEDIA_ERR_SRC_NOT_SUPPORTED = 4;
  readonly attribute unsigned short code;
};
media . error . code

Returns the current error's error code, from the list below.

The code attribute of a MediaError object must return the code for the error, which must be one of the following:

MEDIA_ERR_ABORTED (numeric value 1)
The fetching process for the media resource was aborted by the user agent at the user's request.
MEDIA_ERR_NETWORK (numeric value 2)
A network error of some description caused the user agent to stop fetching the media resource, after the resource was established to be usable.
MEDIA_ERR_DECODE (numeric value 3)
An error of some description occurred while decoding the media resource, after the resource was established to be usable.
MEDIA_ERR_SRC_NOT_SUPPORTED (numeric value 4)
The media resource indicated by the src attribute was not suitable.
3.8.10.2 Location of the media resource

Status: Last call for comments

The src content attribute on media elements gives the address of the media resource (video, audio) to show. The attribute, if present, must contain a valid URL.

If a src attribute of a media element is set or changed, the user agent must invoke the media element's media element load algorithm. (Removing the src attribute does not do this, even if there are source elements present.)

The src IDL attribute on media elements must reflect the content attribute of the same name.

media . currentSrc

Returns the address of the current media resource.

Returns the empty string when there is no media resource.

The currentSrc IDL attribute is initially the empty string. Its value is changed by the resource selection algorithm defined below.

There are two ways to specify a media resource, the src attribute, or source elements. The attribute overrides the elements.

3.8.10.3 MIME types

Status: Last call for comments

A media resource can be described in terms of its type, specifically a MIME type, optionally with a codecs parameter. [RFC4281]

Types are usually somewhat incomplete descriptions; for example "video/mpeg" doesn't say anything except what the container type is, and even a type like "video/mp4; codecs="avc1.42E01E, mp4a.40.2"" doesn't include information like the actual bitrate (only the maximum bitrate). Thus, given a type, a user agent can often only know whether it might be able to play media of that type (with varying levels of confidence), or whether it definitely cannot play media of that type.

A type that the user agent knows it cannot render is one that describes a resource that the user agent definitely does not support, for example because it doesn't recognize the container type, or it doesn't support the listed codecs.

The MIME type "application/octet-stream" with no parameters is never a type that the user agent knows it cannot render. User agents must treat that type as equivalent to the lack of any explicit Content-Type metadata when it is used to label a potential media resource.

In the absence of a specification to the contrary, the MIME type "application/octet-stream" when used with parameters, e.g. "application/octet-stream;codecs=theora", is a type that the user agent knows it cannot render.

media . canPlayType(type)

Returns the empty string (a negative response), "maybe", or "probably" based on how confident the user agent is that it can play media resources of the given type.

The canPlayType(type) method must return the empty string if type is a type that the user agent knows it cannot render; it must return "probably" if the user agent is confident that the type represents a media resource that it can render if used in with this audio or video element; and it must return "maybe" otherwise. Implementors are encouraged to return "maybe" unless the type can be confidently established as being supported or not. Generally, a user agent should never return "probably" if the type doesn't have a codecs parameter.

This script tests to see if the user agent supports a (fictional) new format to dynamically decide whether to use a video element or a plugin:

<section id="video">
 <p><a href="playing-cats.nfv">Download video</a></p>
</section>
<script>
 var videoSection = document.getElementById('video');
 var videoElement = document.createElement('video');
 var support = videoElement.canPlayType('video/x-new-fictional-format;codecs="kittens,bunnies"');
 if (support != "probably" && "New Fictional Video Plug-in" in navigator.plugins) {
   // not confident of browser support
   // but we have a plugin
   // so use plugin instead
   videoElement = document.createElement("embed");
 } else if (support == "") {
   // no support from browser and no plugin
   // do nothing
   videoElement = null;
 }
 if (videoElement) {
   while (videoSection.hasChildNodes())
     videoSection.removeChild(videoSection.firstChild);
   videoElement.setAttribute("src", "playing-cats.nfv");
   videoSection.appendChild(videoElement);
 }
</script>

The type attribute of the source element allows the user agent to avoid downloading resources that use formats it cannot render.

3.8.10.4 Network states

Status: Last call for comments

media . networkState

Returns the current state of network activity for the element, from the codes in the list below.

As media elements interact with the network, their current network activity is represented by the networkState attribute. On getting, it must return the current network state of the element, which must be one of the following values:

NETWORK_EMPTY (numeric value 0)
The element has not yet been initialized. All attributes are in their initial states.
NETWORK_IDLE (numeric value 1)
The element's resource selection algorithm is active and has selected a resource, but it is not actually using the network at this time.
NETWORK_LOADING (numeric value 2)
The user agent is actively trying to download data.
NETWORK_NO_SOURCE (numeric value 3)
The element's resource selection algorithm is active, but it has failed to find a resource to use.

The resource selection algorithm defined below describes exactly when the networkState attribute changes value and what events fire to indicate changes in this state.

3.8.10.5 Loading the media resource

Status: Last call for comments

media . load()

Causes the element to reset and start selecting and loading a new media resource from scratch.

All media elements have an autoplaying flag, which must begin in the true state, and a delaying-the-load-event flag, which must begin in the false state. While the delaying-the-load-event flag is true, the element must delay the load event of its document.

When the load() method on a media element is invoked, the user agent must run the media element load algorithm.

The media element load algorithm consists of the following steps.

  1. Abort any already-running instance of the resource selection algorithm for this element.

  2. If there are any tasks from the media element's media element event task source in one of the task queues, then remove those tasks.

    Basically, pending events and callbacks for the media element are discarded when the media element starts loading a new resource.

  3. If the media element's networkState is set to NETWORK_LOADING or NETWORK_IDLE, queue a task to fire a simple event named abort at the media element.

  4. If the media element's networkState is not set to NETWORK_EMPTY, then run these substeps:

    1. If a fetching process is in progress for the media element, the user agent should stop it.

    2. Set the networkState attribute to NETWORK_EMPTY.
    3. If readyState is not set to HAVE_NOTHING, then set it to that state.
    4. If the paused attribute is false, then set to true.
    5. If seeking is true, set it to false.
    6. Set the current playback position to 0.
    7. Queue a task to fire a simple event named emptied at the media element.

  5. Set the playbackRate attribute to the value of the defaultPlaybackRate attribute.

  6. Set the error attribute to null and the autoplaying flag to true.

  7. Invoke the media element's resource selection algorithm.

  8. Playback of any previously playing media resource for this element stops.

The resource selection algorithm for a media element is as follows. This algorithm is always invoked synchronously, but one of the first steps in the algorithm is to return and continue running the remaining steps asynchronously, meaning that it runs in the background with scripts and other tasks running in parallel. In addition, this algorithm interacts closely with the event loop mechanism; in particular, it has synchronous sections (which are triggered as part of the event loop algorithm). Steps in such sections are marked with ⌛.

  1. Set the networkState to NETWORK_NO_SOURCE.

  2. Asynchronously await a stable state, allowing the task that invoked this algorithm to continue. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended. (Steps in synchronous sections are marked with ⌛.)

  3. ⌛ If the media element has a src attribute, then let mode be attribute.

    ⌛ Otherwise, if the media element does not have a src attribute but has a source element child, then let mode be children and let candidate be the first such source element child in tree order.

    ⌛ Otherwise the media element has neither a src attribute nor a source element child: set the networkState to NETWORK_EMPTY, and abort these steps; the synchronous section ends.

  4. ⌛ Set the media element's delaying-the-load-event flag to true (this delays the load event), and set its networkState to NETWORK_LOADING.

  5. Queue a task to fire a simple event named loadstart at the media element.

  6. If mode is attribute, then run these substeps:

    1. ⌛ Let absolute URL be the absolute URL that would have resulted from resolving the URL specified by the src attribute's value relative to the media element when the src attribute was last changed.

    2. ⌛ If absolute URL was obtained successfully, set the currentSrc attribute to absolute URL.

    3. End the synchronous section, continuing the remaining steps asynchronously.

    4. If absolute URL was obtained successfully, run the resource fetch algorithm with absolute URL. If that algorithm returns without aborting this one, then the load failed.

    5. Reaching this step indicates that the media resource failed to load or that the given URL could not be resolved. Set the error attribute to a new MediaError object whose code attribute is set to MEDIA_ERR_SRC_NOT_SUPPORTED.

    6. Set the element's networkState attribute to the NETWORK_NO_SOURCE value.

    7. Queue a task to fire a simple event named error at the media element.

    8. Set the element's delaying-the-load-event flag to false. This stops delaying the load event.

    9. Abort these steps. Until the load() method is invoked or the src attribute is changed, the element won't attempt to load another resource.

    Otherwise, the source elements will be used; run these substeps:

    1. ⌛ Let pointer be a position defined by two adjacent nodes in the media element's child list, treating the start of the list (before the first child in the list, if any) and end of the list (after the last child in the list, if any) as nodes in their own right. One node is the node before pointer, and the other node is the node after pointer. Initially, let pointer be the position between the candidate node and the next node, if there are any, or the end of the list, if it is the last node.

      As nodes are inserted and removed into the media element, pointer must be updated as follows:

      If a new node is inserted between the two nodes that define pointer
      Let pointer be the point between the node before pointer and the new node. In other words, insertions at pointer go after pointer.
      If the node before pointer is removed
      Let pointer be the point between the node after pointer and the node before the node after pointer. In other words, pointer doesn't move relative to the remaining nodes.
      If the node after pointer is removed
      Let pointer be the point between the node before pointer and the node after the node before pointer. Just as with the previous case, pointer doesn't move relative to the remaining nodes.

      Other changes don't affect pointer.

    2. Process candidate: If candidate does not have a src attribute, then end the synchronous section, and jump down to the failed step below.

    3. ⌛ Let absolute URL be the absolute URL that would have resulted from resolving the URL specified by candidate's src attribute's value relative to the candidate when the src attribute was last changed.

    4. ⌛ If absolute URL was not obtained successfully, then end the synchronous section, and jump down to the failed step below.

    5. ⌛ If candidate has a type attribute whose value, when parsed as a MIME type (including any codecs described by the codecs parameter), represents a type that the user agent knows it cannot render, then end the synchronous section, and jump down to the failed step below.

    6. ⌛ If candidate has a media attribute whose value does not match the environment of the default view, then end the synchronous section, and jump down to the failed step below.

    7. ⌛ Set the currentSrc attribute to absolute URL.

    8. End the synchronous section, continuing the remaining steps asynchronously.

    9. Run the resource fetch algorithm with absolute URL. If that algorithm returns without aborting this one, then the load failed.

    10. Failed: Queue a task to fire a simple event named error at the candidate element, in the context of the fetching process that was used to try to obtain candidate's corresponding media resource in the resource fetch algorithm.

    11. Asynchronously await a stable state. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended. (Steps in synchronous sections are marked with ⌛.)

    12. Find next candidate: Let candidate be null.

    13. Search loop: If the node after pointer is the end of the list, then jump to the waiting step below.

    14. ⌛ If the node after pointer is a source element, let candidate be that element.

    15. ⌛ Advance pointer so that the node before pointer is now the node that was after pointer, and the node after pointer is the node after the node that used to be after pointer, if any.

    16. ⌛ If candidate is null, jump back to the search loop step. Otherwise, jump back to the process candidate step.

    17. Waiting: Set the element's networkState attribute to the NETWORK_NO_SOURCE value.

    18. ⌛ Set the element's delaying-the-load-event flag to false. This stops delaying the load event.

    19. End the synchronous section, continuing the remaining steps asynchronously.

    20. Wait until the node after pointer is a node other than the end of the list. (This step might wait forever.)

    21. Asynchronously await a stable state. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended. (Steps in synchronous sections are marked with ⌛.)

    22. ⌛ Set the element's delaying-the-load-event flag back to true (this delays the load event again, in case it hasn't been fired yet).

    23. ⌛ Set the networkState back to NETWORK_LOADING.

    24. ⌛ Jump back to the find next candidate step above.

The resource fetch algorithm for a media element and a given absolute URL is as follows:

  1. Let the current media resource be the resource given by the absolute URL passed to this algorithm. This is now the element's media resource.

  2. Begin to fetch the current media resource, from the media element's Document's origin.

    Every 350ms (±200ms) or for every byte received, whichever is least frequent, queue a task to fire a simple event named progress at the element.

    If at any point the user agent has received no data for more than about three seconds, then queue a task to fire a simple event named stalled at the element.

    User agents may allow users to selectively block or slow media data downloads. When a media element's download has been blocked altogether, the user agent must act as if it was stalled (as opposed to acting as if the connection was closed). The rate of the download may also be throttled automatically by the user agent, e.g. to balance the download with other connections sharing the same bandwidth.

    User agents may decide to not download more content at any time, e.g. after buffering five minutes of a one hour media resource, while waiting for the user to decide whether to play the resource or not, or while waiting for user input in an interactive resource. When a media element's download has been suspended, the user agent must set the networkState to NETWORK_IDLE and queue a task to fire a simple event named suspend at the element. If and when downloading of the resource resumes, the user agent must set the networkState to NETWORK_LOADING.

    The autobuffer attribute provides a hint that the author expects that downloading the entire resource optimistically will be worth it, even in the absence of the autoplay attribute. In the absence of either attribute, the user agent is likely to find that waiting until the user starts playback before downloading any further content leads to a more efficient use of the network resources.

    When a user agent decides to completely stall a download, e.g. if it is waiting until the user starts playback before downloading any further content, the element's delaying-the-load-event flag must be set to false. This stops delaying the load event.

    The user agent may use whatever means necessary to fetch the resource (within the constraints put forward by this and other specifications); for example, reconnecting to the server in the face of network errors, using HTTP range retrieval requests, or switching to a streaming protocol. The user agent must consider a resource erroneous only if it has given up trying to fetch it.

    The networking task source tasks to process the data as it is being fetched must, when appropriate, include the relevant substeps from the following list:

    If the media data cannot be fetched at all, due to network errors, causing the user agent to give up trying to fetch the resource
    If the media resource is found to have Content-Type metadata that, when parsed as a MIME type (including any codecs described by the codecs parameter), represents a type that the user agent knows it cannot render (even if the actual media data is in a supported format)
    If the media data can be fetched but is found by inspection to be in an unsupported format, or can otherwise not be rendered at all

    DNS errors, HTTP 4xx and 5xx errors (and equivalents in other protocols), and other fatal network errors that occur before the user agent has established whether the current media resource is usable, as well as the file using an unsupported container format, or using unsupported codecs for all the data, must cause the user agent to execute the following steps:

    1. The user agent should cancel the fetching process.

    2. Abort this subalgorithm, returning to the resource selection algorithm.

    Once enough of the media data has been fetched to determine the duration of the media resource, its dimensions, and other metadata

    This indicates that the resource is usable. The user agent must follow these substeps:

    1. Set the current playback position to the earliest possible position.

    2. Set the readyState attribute to HAVE_METADATA.

    3. For video elements, set the videoWidth and videoHeight attributes.

    4. Set the duration attribute to the duration of the resource.

      The user agent will queue a task to fire a simple event named durationchange at the element at this point.

    5. Queue a task to fire a simple event named loadedmetadata at the element.

      Before this task is run, as part of the event loop mechanism, the rendering will have been updated to resize the video element if appropriate.

    6. If either the media resource or the address of the current media resource indicate a particular start time, then seek to that time. Ignore any resulting exceptions (if the position is out of range, it is effectively ignored).

      For example, a fragment identifier could be used to indicate a start position.

    7. Once the readyState attribute reaches HAVE_CURRENT_DATA, after the loadeddata event has been fired, set the element's delaying-the-load-event flag to false. This stops delaying the load event.

      A user agent that is attempting to reduce network usage while still fetching the metadata for each media resource would also stop buffering at this point, causing the networkState attribute to switch to the NETWORK_IDLE value, if the media element did not have an autobuffer or autoplay attribute.

    The user agent is required to determine the duration of the media resource and go through this step before playing.

    Once the entire media resource has been fetched (but potentially before any of it has been decoded)

    Queue a task to fire a simple event named progress at the media element.

    If the connection is interrupted, causing the user agent to give up trying to fetch the resource

    Fatal network errors that occur after the user agent has established whether the current media resource is usable must cause the user agent to execute the following steps:

    1. The user agent should cancel the fetching process.

    2. Set the error attribute to a new MediaError object whose code attribute is set to MEDIA_ERR_NETWORK.

    3. Queue a task to fire a simple event named error at the media element.

    4. Set the element's networkState attribute to the NETWORK_EMPTY value and queue a task to fire a simple event named emptied at the element.

    5. Set the element's delaying-the-load-event flag to false. This stops delaying the load event.

    6. Abort the overall resource selection algorithm.

    If the media data is corrupted

    Fatal errors in decoding the media data that occur after the user agent has established whether the current media resource is usable must cause the user agent to execute the following steps:

    1. The user agent should cancel the fetching process.

    2. Set the error attribute to a new MediaError object whose code attribute is set to MEDIA_ERR_DECODE.

    3. Queue a task to fire a simple event named error at the media element.

    4. Set the element's networkState attribute to the NETWORK_EMPTY value and queue a task to fire a simple event named emptied at the element.

    5. Set the element's delaying-the-load-event flag to false. This stops delaying the load event.

    6. Abort the overall resource selection algorithm.

    If the media data fetching process is aborted by the user

    The fetching process is aborted by the user, e.g. because the user navigated the browsing context to another page, the user agent must execute the following steps. These steps are not followed if the load() method itself is invoked while these steps are running, as the steps above handle that particular kind of abort.

    1. The user agent should cancel the fetching process.

    2. Set the error attribute to a new MediaError object whose code attribute is set to MEDIA_ERR_ABORT.

    3. Queue a task to fire a simple event named abort at the media element.

    4. If the media element's readyState attribute has a value equal to HAVE_NOTHING, set the element's networkState attribute to the NETWORK_EMPTY value and queue a task to fire a simple event named emptied at the element. Otherwise, set the element's networkState attribute to the NETWORK_IDLE value.

    5. Set the element's delaying-the-load-event flag to false. This stops delaying the load event.

    6. Abort the overall resource selection algorithm.

    If the media data can be fetched but has non-fatal errors or uses, in part, codecs that are unsupported, preventing the user agent from rendering the content completely correctly but not preventing playback altogether

    The server returning data that is partially usable but cannot be optimally rendered must cause the user agent to render just the bits it can handle, and ignore the rest.

    When the networking task source has queued the last task as part of fetching the media resource (i.e. once the download has completed), if the fetching process completes without errors, including decoding the media data, and if all of the data is available to the user agent without network access, then, the user agent must move on to the next step. This might never happen, e.g. when streaming an infinite resource such as Web radio, or if the resource is longer than the user agent's ability to cache data.

    While the user agent might still need network access to obtain parts of the media resource, the user agent must remain on this step.

    For example, if the user agent has discarded the first half of a video, the user agent will remain at this step even once the playback has ended, because there is always the chance the user will seek back to the start. In fact, in this situation, once playback has ended, the user agent will end up dispatching a stalled event, as described earlier.

  3. If the user agent ever reaches this step (which can only happen if the entire resource gets loaded and kept available): abort the overall resource selection algorithm.

The autobuffer attribute is a boolean attribute. Its presence hints to the user agent that the author believes that the media element will likely be used, even though the element does not have an autoplay attribute. (The attribute has no effect if used in conjunction with the autoplay attribute, though including both is not an error.) This attribute may be ignored altogether. The attribute must be ignored if the autoplay attribute is present.

The autobuffer IDL attribute must reflect the content attribute of the same name.

media . buffered

Returns a TimeRanges object that represents the ranges of the media resource that the user agent has buffered.

The buffered attribute must return a new static normalized TimeRanges object that represents the ranges of the media resource, if any, that the user agent has buffered, at the time the attribute is evaluated. Users agents must accurately determine the ranges available, even for media streams where this can only be determined by tedious inspection.

Typically this will be a single range anchored at the zero point, but if, e.g. the user agent uses HTTP range requests in response to seeking, then there could be multiple ranges.

User agents may discard previously buffered data.

Thus, a time position included within a range of the objects return by the buffered attribute at one time can end up being not included in the range(s) of objects returned by the same attribute at later times.

3.8.10.6 Offsets into the media resource

Status: Last call for comments

media . duration

Returns the length of the media resource, in seconds.

Returns NaN if the duration isn't available.

Returns Infinity for unbounded streams.

media . currentTime [ = value ]

Returns the current playback position, in seconds.

Can be set, to seek to the given time.

Will throw an INVALID_STATE_ERR exception if there is no selected media resource. Will throw an INDEX_SIZE_ERR exception if the given time is not within the ranges to which the user agent can seek.

media . startTime

Returns the earliest possible position, in seconds. This is the time for the start of the current clip. It might not be zero if the clip's timeline is not zero-based, or if the resource is a streaming resource (in which case it gives the earliest time that the user agent is able to seek back to).

The duration attribute must return the length of the media resource, in seconds. If no media data is available, then the attributes must return the Not-a-Number (NaN) value. If the media resource is known to be unbounded (e.g. a streaming radio), then the attribute must return the positive Infinity value.

The user agent must determine the duration of the media resource before playing any part of the media data and before setting readyState to a value equal to or greater than HAVE_METADATA, even if doing so requires seeking to multiple parts of the resource.

When the length of the media resource changes (e.g. from being unknown to known, or from a previously established length to a new length) the user agent must queue a task to fire a simple event named durationchange at the media element.

If an "infinite" stream ends for some reason, then the duration would change from positive Infinity to the time of the last frame or sample in the stream, and the durationchange event would be fired. Similarly, if the user agent initially estimated the media resource's duration instead of determining it precisely, and later revises the estimate based on new information, then the duration would change and the durationchange event would be fired.

Media elements have a current playback position, which must initially be zero. The current position is a time.

The currentTime attribute must, on getting, return the current playback position, expressed in seconds. On setting, the user agent must seek to the new value (which might raise an exception).

If the media resource is a streaming resource, then the user agent might be unable to obtain certain parts of the resource after it has expired from its buffer. Similarly, some media resources might have a timeline that doesn't start at zero. The earliest possible position is the earliest position in the stream or resource that the user agent can ever obtain again.

The startTime attribute must, on getting, return the earliest possible position, expressed in seconds.

When the earliest possible position changes, then: if the current playback position is before the earliest possible position, the user agent must seek to the earliest possible position; otherwise, if the user agent has not fired a timeupdate event at the element in the past 15 to 250ms, then the user agent must queue a task to fire a simple event named timeupdate at the element.

Because of the above requirement and the requirement in the resource fetch algorithm that kicks in when the metadata of the clip becomes known, the current playback position can never be less than the earliest possible position.

User agents must act as if the timeline of the media resource increases linearly starting from the earliest possible position, even if the underlying media data has out-of-order or even overlapping time codes.

For example, if two clips have been concatenated into one video file, but the video format exposes the original times for the two clips, the video data might expose a timeline that goes, say, 00:15..00:29 and then 00:05..00:38. However, the user agent would not expose those times; it would instead expose the times as 00:15..00:29 and 00:29..01:02, as a single video.

The loop attribute is a boolean attribute that, if specified, indicates that the media element is to seek back to the start of the media resource upon reaching the end.

The loop IDL attribute must reflect the content attribute of the same name.

3.8.10.7 The ready states

Status: Last call for comments

media . readyState

Returns a value that expresses the current state of the element with respect to rendering the current playback position, from the codes in the list below.

Media elements have a ready state, which describes to what degree they are ready to be rendered at the current playback position. The possible values are as follows; the ready state of a media element at any particular time is the greatest value describing the state of the element:

HAVE_NOTHING (numeric value 0)
No information regarding the media resource is available. No data for the current playback position is available. Media elements whose networkState attribute is NETWORK_EMPTY are always in the HAVE_NOTHING state.
HAVE_METADATA (numeric value 1)
Enough of the resource has been obtained that the duration of the resource is available. In the case of a video element, the dimensions of the video are also available. The API will no longer raise an exception when seeking. No media data is available for the immediate current playback position.
HAVE_CURRENT_DATA (numeric value 2)
Data for the immediate current playback position is available, but either not enough data is available that the user agent could successfully advance the current playback position in the direction of playback at all without immediately reverting to the HAVE_METADATA state, or there is no more data to obtain in the direction of playback. For example, in video this corresponds to the user agent having data from the current frame, but not the next frame; and to when playback has ended.
HAVE_FUTURE_DATA (numeric value 3)
Data for the immediate current playback position is available, as well as enough data for the user agent to advance the current playback position in the direction of playback at least a little without immediately reverting to the HAVE_METADATA state. For example, in video this corresponds to the user agent having data for at least the current frame and the next frame. The user agent cannot be in this state if playback has ended, as the current playback position can never advance in this case.
HAVE_ENOUGH_DATA (numeric value 4)
All the conditions described for the HAVE_FUTURE_DATA state are met, and, in addition, the user agent estimates that data is being fetched at a rate where the current playback position, if it were to advance at the rate given by the defaultPlaybackRate attribute, would not overtake the available data before playback reaches the end of the media resource.

When the ready state of a media element whose networkState is not NETWORK_EMPTY changes, the user agent must follow the steps given below:

If the previous ready state was HAVE_NOTHING, and the new ready state is HAVE_METADATA

A loadedmetadata DOM event will be fired as part of the load() algorithm.

If the previous ready state was HAVE_METADATA and the new ready state is HAVE_CURRENT_DATA or greater

If this is the first time this occurs for this media element since the load() algorithm was last invoked, the user agent must queue a task to fire a simple event named loadeddata at the element.

If the new ready state is HAVE_FUTURE_DATA or HAVE_ENOUGH_DATA, then the relevant steps below must then be run also.

If the previous ready state was HAVE_FUTURE_DATA or more, and the new ready state is HAVE_CURRENT_DATA or less

A waiting DOM event can be fired, depending on the current state of playback.

If the previous ready state was HAVE_CURRENT_DATA or less, and the new ready state is HAVE_FUTURE_DATA

The user agent must queue a task to fire a simple event named canplay.

If the element is potentially playing, the user agent must queue a task to fire a simple event named playing.

If the new ready state is HAVE_ENOUGH_DATA

If the previous ready state was HAVE_CURRENT_DATA or less, the user agent must queue a task to fire a simple event named canplay, and, if the element is also potentially playing, queue a task to fire a simple event named playing.

If the autoplaying flag is true, and the paused attribute is true, and the media element has an autoplay attribute specified, then the user agent may also set the paused attribute to false, queue a task to fire a simple event named play, and queue a task to fire a simple event named playing.

User agents are not required to autoplay, and it is suggested that user agents honor user preferences on the matter. Authors are urged to use the autoplay attribute rather than using script to force the video to play, so as to allow the user to override the behavior if so desired.

In any case, the user agent must finally queue a task to fire a simple event named canplaythrough.

It is possible for the ready state of a media element to jump between these states discontinuously. For example, the state of a media element can jump straight from HAVE_METADATA to HAVE_ENOUGH_DATA without passing through the HAVE_CURRENT_DATA and HAVE_FUTURE_DATA states.

The readyState IDL attribute must, on getting, return the value described above that describes the current ready state of the media element.

The autoplay attribute is a boolean attribute. When present, the user agent (as described in the algorithm described herein) will automatically begin playback of the media resource as soon as it can do so without stopping.

Authors are urged to use the autoplay attribute rather than using script to trigger automatic playback, as this allows the user to override the automatic playback when it is not desired, e.g. when using a screen reader. Authors are also encouraged to consider not using the automatic playback behavior at all, and instead to let the user agent wait for the user to start playback explicitly.

The autoplay IDL attribute must reflect the content attribute of the same name.

3.8.10.8 Playing the media resource

Status: Last call for comments

media . paused

Returns true if playback is paused; false otherwise.

media . ended

Returns true if playback has reached the end of the media resource.

media . defaultPlaybackRate [ = value ]

Returns the default rate of playback, for when the user is not fast-forwarding or reversing through the media resource.

Can be set, to change the default rate of playback.

The default rate has no direct effect on playback, but if the user switches to a fast-forward mode, when they return to the normal playback mode, it is expected that the rate of playback will be returned to the default rate of playback.

media . playbackRate [ = value ]

Returns the current rate playback, where 1.0 is normal speed.

Can be set, to change the rate of playback.

media . played

Returns a TimeRanges object that represents the ranges of the media resource that the user agent has played.

media . play()

Sets the paused attribute to false, loading the media resource and beginning playback if necessary. If the playback had ended, will restart it from the start.

media . pause()

Sets the paused attribute to true, loading the media resource if necessary.

The paused attribute represents whether the media element is paused or not. The attribute must initially be true.

A media element is said to be potentially playing when its paused attribute is false, the readyState attribute is either HAVE_FUTURE_DATA or HAVE_ENOUGH_DATA, the element has not ended playback, playback has not stopped due to errors, and the element has not paused for user interaction.

A media element is said to have ended playback when the element's readyState attribute is HAVE_METADATA or greater, and either the current playback position is the end of the media resource and the direction of playback is forwards and the media element does not have a loop attribute specified, or the current playback position is the earliest possible position and the direction of playback is backwards.

The ended attribute must return true if the media element has ended playback and the direction of playback is forwards, and false otherwise.

A media element is said to have stopped due to errors when the element's readyState attribute is HAVE_METADATA or greater, and the user agent encounters a non-fatal error during the processing of the media data, and due to that error, is not able to play the content at the current playback position.

A media element is said to have paused for user interaction when its paused attribute is false, the readyState attribute is either HAVE_FUTURE_DATA or HAVE_ENOUGH_DATA and the user agent has reached a point in the media resource where the user has to make a selection for the resource to continue.

It is possible for a media element to have both ended playback and paused for user interaction at the same time.

When a media element that is potentially playing stops playing because it has paused for user interaction, the user agent must queue a task to fire a simple event named timeupdate at the element.

When a media element that is potentially playing stops playing because its readyState attribute changes to a value lower than HAVE_FUTURE_DATA, without the element having ended playback, or playback having stopped due to errors, or playback having paused for user interaction, or the seeking algorithm being invoked, the user agent must queue a task to fire a simple event named timeupdate at the element, and queue a task to fire a simple event named waiting at the element.

When the current playback position reaches the end of the media resource when the direction of playback is forwards, then the user agent must follow these steps:

  1. If the media element has a loop attribute specified, then seek to the earliest possible position of the media resource and abort these steps.

  2. Stop playback.

    The ended attribute becomes true.

  3. The user agent must queue a task to fire a simple event named timeupdate at the element.

  4. The user agent must queue a task to fire a simple event named ended at the element.

When the current playback position reaches the earliest possible position of the media resource when the direction of playback is backwards, then the user agent must follow these steps:

  1. Stop playback.

  2. The user agent must queue a task to fire a simple event named timeupdate at the element.

The defaultPlaybackRate attribute gives the desired speed at which the media resource is to play, as a multiple of its intrinsic speed. The attribute is mutable: on getting it must return the last value it was set to, or 1.0 if it hasn't yet been set; on setting the attribute must be set to the new value.

The playbackRate attribute gives the speed at which the media resource plays, as a multiple of its intrinsic speed. If it is not equal to the defaultPlaybackRate, then the implication is that the user is using a feature such as fast forward or slow motion playback. The attribute is mutable: on getting it must return the last value it was set to, or 1.0 if it hasn't yet been set; on setting the attribute must be set to the new value, and the playback must change speed (if the element is potentially playing).

If the playbackRate is positive or zero, then the direction of playback is forwards. Otherwise, it is backwards.

The "play" function in a user agent's interface must set the playbackRate attribute to the value of the defaultPlaybackRate attribute before invoking the play() method's steps. Features such as fast-forward or rewind must be implemented by only changing the playbackRate attribute.

When the defaultPlaybackRate or playbackRate attributes change value (either by being set by script or by being changed directly by the user agent, e.g. in response to user control) the user agent must queue a task to fire a simple event named ratechange at the media element.

The played attribute must return a new static normalized TimeRanges object that represents the ranges of the media resource, if any, that the user agent has so far rendered, at the time the attribute is evaluated.


When the play() method on a media element is invoked, the user agent must run the following steps.

  1. If the media element's networkState attribute has the value NETWORK_EMPTY, invoke the media element's resource selection algorithm.

  2. If the playback has ended, seek to the earliest possible position of the media resource.

    This will cause the user agent to queue a task to fire a simple event named timeupdate at the media element.

  3. If the media element's paused attribute is true, run the following substeps:

    1. Change the value of paused to false.

    2. Queue a task to fire a simple event named play at the element.

    3. If the media element's readyState attribute has the value HAVE_NOTHING, HAVE_METADATA, or HAVE_CURRENT_DATA, queue a task to fire a simple event named waiting at the element.

    4. Otherwise, the media element's readyState attribute has the value HAVE_FUTURE_DATA or HAVE_ENOUGH_DATA; queue a task to fire a simple event named playing at the element.

  4. Set the media element's autoplaying flag to false.


When the pause() method is invoked, the user agent must run the following steps:

  1. If the media element's networkState attribute has the value NETWORK_EMPTY, invoke the media element's resource selection algorithm.

  2. Set the media element's autoplaying flag to false.

  3. If the media element's paused attribute is false, run the following steps:

    1. Change the value of paused to true.

    2. Queue a task to fire a simple event named timeupdate at the element.

    3. Queue a task to fire a simple event named pause at the element.


When a media element is potentially playing and its Document is a fully active Document, its current playback position must increase monotonically at playbackRate units of media time per unit time of wall clock time.

This specification doesn't define how the user agent achieves the appropriate playback rate — depending on the protocol and media available, it is plausible that the user agent could negotiate with the server to have the server provide the media data at the appropriate rate, so that (except for the period between when the rate is changed and when the server updates the stream's playback rate) the client doesn't actually have to drop or interpolate any frames.

When the playbackRate is negative (playback is backwards), any corresponding audio must be muted. When the playbackRate is so low or so high that the user agent cannot play audio usefully, the corresponding audio must also be muted. If the playbackRate is not 1.0, the user agent may apply pitch adjustments to the audio as necessary to render it faithfully.

The playbackRate can be 0.0, in which case the current playback position doesn't move, despite playback not being paused (paused doesn't become true, and the pause event doesn't fire).

Media elements that are potentially playing while not in a Document must not play any video, but should play any audio component. Media elements must not stop playing just because all references to them have been removed; only once a media element to which no references exist has reached a point where no further audio remains to be played for that element (e.g. because the element is paused, or because the end of the clip has been reached, or because its playbackRate is 0.0) may the element be garbage collected.


When the current playback position of a media element changes (e.g. due to playback or seeking), the user agent must run the following steps. If the current playback position changes while the steps are running, then the user agent must wait for the steps to complete, and then must immediately rerun the steps. (These steps are thus run as often as possible or needed — if one iteration takes a long time, this can cause certain ranges to be skipped over as the user agent rushes ahead to "catch up".)

  1. If the time was reached through the usual monotonic increase of the current playback position during normal playback, and if the user agent has not fired a timeupdate event at the element in the past 15 to 250ms, then the user agent must queue a task to fire a simple event named timeupdate at the element. (In the other cases, such as explicit seeks, relevant events get fired as part of the overall process of changing the current playback position.)

    The event thus is not to be fired faster than about 66Hz or slower than 4Hz. User agents are encouraged to vary the frequency of the event based on the system load and the average cost of processing the event each time, so that the UI updates are not any more frequent than the user agent can comfortably handle while decoding the video.

When a media element is removed from a Document, if the media element's networkState attribute has a value other than NETWORK_EMPTY then the user agent must act as if the pause() method had been invoked.

If the media element's Document stops being a fully active document, then the playback will stop until the document is active again.

3.8.10.9 Seeking

Status: Last call for comments

media . seeking

Returns true if the user agent is currently seeking.

media . seekable

Returns a TimeRanges object that represents the ranges of the media resource to which it is possible for the user agent to seek.

The seeking attribute must initially have the value false.

When the user agent is required to seek to a particular new playback position in the media resource, it means that the user agent must run the following steps:

  1. If the media element's readyState is HAVE_NOTHING, then the user agent must raise an INVALID_STATE_ERR exception (if the seek was in response to a DOM method call or setting of an IDL attribute), and abort these steps.

  2. If the new playback position is later than the end of the media resource, then let it be the end of the media resource instead.

  3. If the new playback position is less than the earliest possible position, let it be that position instead.

  4. If the (possibly now changed) new playback position is not in one of the ranges given in the seekable attribute, then the user agent must raise an INDEX_SIZE_ERR exception (if the seek was in response to a DOM method call or setting of an IDL attribute), and abort these steps.

  5. The current playback position must be set to the given new playback position.

  6. The seeking IDL attribute must be set to true.

  7. The user agent must queue a task to fire a simple event named timeupdate at the element.

  8. If the media element was potentially playing immediately before it started seeking, but seeking caused its readyState attribute to change to a value lower than HAVE_FUTURE_DATA, the user agent must queue a task to fire a simple event named waiting at the element.

  9. If, when it reaches this step, the user agent has still not established whether or not the media data for the new playback position is available, and, if it is, decoded enough data to play back that position, the user agent must queue a task to fire a simple event named seeking at the element.

  10. If the seek was in response to a DOM method call or setting of an IDL attribute, then continue the script. The remainder of these steps must be run asynchronously.

  11. The user agent must wait until it has established whether or not the media data for the new playback position is available, and, if it is, until it has decoded enough data to play back that position.

  12. The seeking IDL attribute must be set to false.

  13. The user agent must queue a task to fire a simple event named seeked at the element.

The seekable attribute must return a new static normalized TimeRanges object that represents the ranges of the media resource, if any, that the user agent is able to seek to, at the time the attribute is evaluated.

If the user agent can seek to anywhere in the media resource, e.g. because it a simple movie file and the user agent and the server support HTTP Range requests, then the attribute would return an object with one range, whose start is the time of the first frame (typically zero), and whose end is the same as the time of the first frame plus the duration attribute's value (which would equal the time of the last frame).

The range might be continuously changing, e.g. if the user agent is buffering a sliding window on an infinite stream. This is the behavior seen with DVRs viewing live TV, for instance.

Media resources might be internally scripted or interactive. Thus, a media element could play in a non-linear fashion. If this happens, the user agent must act as if the algorithm for seeking was used whenever the current playback position changes in a discontinuous fashion (so that the relevant events fire).

3.8.10.10 User interface

Status: Last call for comments

The controls attribute is a boolean attribute. If present, it indicates that the author has not provided a scripted controller and would like the user agent to provide its own set of controls.

If the attribute is present, or if scripting is disabled for the media element, then the user agent should expose a user interface to the user. This user interface should include features to begin playback, pause playback, seek to an arbitrary position in the content (if the content supports arbitrary seeking), change the volume, change the display of closed captions or embedded sign-language tracks, select different audio tracks or turn on audio descriptions, and show the media content in manners more suitable to the user (e.g. full-screen video or in an independent resizable window). Other controls may also be made available.

Even when the attribute is absent, however, user agents may provide controls to affect playback of the media resource (e.g. play, pause, seeking, and volume controls), but such features should not interfere with the page's normal rendering. For example, such features could be exposed in the media element's context menu.

Where possible (specifically, for starting, stopping, pausing, and unpausing playback, for muting or changing the volume of the audio, and for seeking), user interface features exposed by the user agent must be implemented in terms of the DOM API described above, so that, e.g., all the same events fire.

The controls IDL attribute must reflect the content attribute of the same name.


media . volume [ = value ]

Returns the current playback volume, as a number in the range 0.0 to 1.0, where 0.0 is the quietest and 1.0 the loudest.

Can be set, to change the volume.

Throws an INDEX_SIZE_ERR if the new value is not in the range 0.0 .. 1.0.

media . muted [ = value ]

Returns true if audio is muted, overriding the volume attribute, and false if the volume attribute is being honored.

Can be set, to change whether the audio is muted or not.

The volume attribute must return the playback volume of any audio portions of the media element, in the range 0.0 (silent) to 1.0 (loudest). Initially, the volume must be 1.0, but user agents may remember the last set value across sessions, on a per-site basis or otherwise, so the volume may start at other values. On setting, if the new value is in the range 0.0 to 1.0 inclusive, the attribute must be set to the new value and the playback volume must be correspondingly adjusted as soon as possible after setting the attribute, with 0.0 being silent, and 1.0 being the loudest setting, values in between increasing in loudness. The range need not be linear. The loudest setting may be lower than the system's loudest possible setting; for example the user could have set a maximum volume. If the new value is outside the range 0.0 to 1.0 inclusive, then, on setting, an INDEX_SIZE_ERR exception must be raised instead.

The muted attribute must return true if the audio channels are muted and false otherwise. Initially, the audio channels should not be muted (false), but user agents may remember the last set value across sessions, on a per-site basis or otherwise, so the muted state may start as muted (true). On setting, the attribute must be set to the new value; if the new value is true, audio playback for this media resource must then be muted, and if false, audio playback must then be enabled.

Whenever either the muted or volume attributes are changed, the user agent must queue a task to fire a simple event named volumechange at the media element.

3.8.10.11 Time ranges

Status: Last call for comments

Objects implementing the TimeRanges interface represent a list of ranges (periods) of time.

interface TimeRanges {
  readonly attribute unsigned long length;
  float start(in unsigned long index);
  float end(in unsigned long index);
};
media . length

Returns the number of ranges in the object.

time = media . start(index)

Returns the time for the start of the range with the given index.

Throws an INDEX_SIZE_ERR if the index is out of range.

time = media . end(index)

Returns the time for the end of the range with the given index.

Throws an INDEX_SIZE_ERR if the index is out of range.

The length IDL attribute must return the number of ranges represented by the object.

The start(index) method must return the position of the start of the indexth range represented by the object, in seconds measured from the start of the timeline that the object covers.

The end(index) method must return the position of the end of the indexth range represented by the object, in seconds measured from the start of the timeline that the object covers.

These methods must raise INDEX_SIZE_ERR exceptions if called with an index argument greater than or equal to the number of ranges represented by the object.

When a TimeRanges object is said to be a normalized TimeRanges object, the ranges it represents must obey the following criteria:

In other words, the ranges in such an object are ordered, don't overlap, aren't empty, and don't touch (adjacent ranges are folded into one bigger range).

The timelines used by the objects returned by the buffered, seekable and played IDL attributes of media elements must be the same as that element's media resource's timeline.

3.8.10.12 Event summary

Status: Last call for comments

This section is non-normative.

The following events fire on media elements as part of the processing model described above:

Event name Interface Dispatched when... Preconditions
loadstart Event The user agent begins looking for media data, as part of the resource selection algorithm. networkState equals NETWORK_LOADING
progress Event The user agent is fetching media data. networkState equals NETWORK_LOADING
suspend Event The user agent is intentionally not currently fetching media data, but does not have the entire media resource downloaded. networkState equals NETWORK_IDLE
abort Event The user agent stops fetching the media data before it is completely downloaded, but not due to an error. error is an object with the code MEDIA_ERR_ABORTED. networkState equals either NETWORK_EMPTY or NETWORK_IDLE, depending on when the download was aborted.
error Event An error occurs while fetching the media data. error is an object with the code MEDIA_ERR_NETWORK or higher. networkState equals either NETWORK_EMPTY or NETWORK_IDLE, depending on when the download was aborted.
emptied Event A media element whose networkState was previously not in the NETWORK_EMPTY state has just switched to that state (either because of a fatal error during load that's about to be reported, or because the load() method was invoked while the resource selection algorithm was already running, in which case it is fired synchronously during the load() method call). networkState is NETWORK_EMPTY; all the IDL attributes are in their initial states.
stalled Event The user agent is trying to fetch media data, but data is unexpectedly not forthcoming. networkState is NETWORK_LOADING.
play Event Playback has begun. Fired after the play() method has returned. paused is newly false.
pause Event Playback has been paused. Fired after the pause method has returned. paused is newly true.
loadedmetadata Event The user agent has just determined the duration and dimensions of the media resource. readyState is newly equal to HAVE_METADATA or greater for the first time.
loadeddata Event The user agent can render the media data at the current playback position for the first time. readyState newly increased to HAVE_CURRENT_DATA or greater for the first time.
waiting Event Playback has stopped because the next frame is not available, but the user agent expects that frame to become available in due course. readyState is newly equal to or less than HAVE_CURRENT_DATA, and paused is false. Either seeking is true, or the current playback position is not contained in any of the ranges in buffered. It is possible for playback to stop for two other reasons without paused being false, but those two reasons do not fire this event: maybe playback ended, or playback stopped due to errors.
playing Event Playback has started. readyState is newly equal to or greater than HAVE_FUTURE_DATA, paused is false, seeking is false, or the current playback position is contained in one of the ranges in buffered.
canplay Event The user agent can resume playback of the media data, but estimates that if playback were to be started now, the media resource could not be rendered at the current playback rate up to its end without having to stop for further buffering of content. readyState newly increased to HAVE_FUTURE_DATA or greater.
canplaythrough Event The user agent estimates that if playback were to be started now, the media resource could be rendered at the current playback rate all the way to its end without having to stop for further buffering. readyState is newly equal to HAVE_ENOUGH_DATA.
seeking Event The seeking IDL attribute changed to true and the seek operation is taking long enough that the user agent has time to fire the event.
seeked Event The seeking IDL attribute changed to false.
timeupdate Event The current playback position changed as part of normal playback or in an especially interesting way, for example discontinuously.
ended Event Playback has stopped because the end of the media resource was reached. currentTime equals the end of the media resource; ended is true.
ratechange Event Either the defaultPlaybackRate or the playbackRate attribute has just been updated.
durationchange Event The duration attribute has just been updated.
volumechange Event Either the volume attribute or the muted attribute has changed. Fired after the relevant attribute's setter has returned.
3.8.10.13 Security and privacy considerations

Status: Last call for comments

The main security and privacy implications of the video and audio elements come from the ability to embed media cross-origin. There are two directions that threats can flow: from hostile content to a victim page, and from a hostile page to victim content.


If a victim page embeds hostile content, the threat is that the content might contain scripted code that attempts to interact with the Document that embeds the content. To avoid this, user agents must ensure that there is no access from the content to the embedding page. In the case of media content that uses DOM concepts, the embedded content must be treated as if it was in its own unrelated top-level browsing context.

For instance, if an SVG animation was embedded in a video element, the user agent would not give it access to the DOM of the outer page. From the perspective of scripts in the SVG resource, the SVG file would appear to be in a lone top-level browsing context with no parent.


If a hostile page embeds victim content, the threat is that the embedding page could obtain information from the content that it would not otherwise have access to. The API does expose some information: the existence of the media, its type, its duration, its size, and the performance characteristics of its host. Such information is already potentially problematic, but in practice the same information can more or less be obtained using the img element, and so it has been deemed acceptable.

However, significantly more sensitive information could be obtained if the user agent further exposes metadata within the content such as subtitles or chapter titles. This version of the API does not expose such information. Future extensions to this API will likely reuse a mechanism such as CORS to check that the embedded content's site has opted in to exposing such information. [CORS]

An attacker could trick a user running within a corporate network into visiting a site that attempts to load a video from a previously leaked location on the corporation's intranet. If such a video included confidential plans for a new product, then being able to read the subtitles would present a confidentiality breach.

3.8.11 The canvas element

Status: Last call for comments. ISSUE-74 (canvas-accessibility) blocks progress to Last Call

Categories
Flow content.
Phrasing content.
Embedded content.
Contexts in which this element may be used:
Where embedded content is expected.
Content model:
Transparent.
Content attributes:
Global attributes
width
height
DOM interface:
interface HTMLCanvasElement : HTMLElement {
           attribute unsigned long width;
           attribute unsigned long height;

  DOMString toDataURL(in optional DOMString type, in any... args);

  object getContext(in DOMString contextId);
};

The canvas element provides scripts with a resolution-dependent bitmap canvas, which can be used for rendering graphs, game graphics, or other visual images on the fly.

Authors should not use the canvas element in a document when a more suitable element is available. For example, it is inappropriate to use a canvas element to render a page heading: if the desired presentation of the heading is graphically intense, it should be marked up using appropriate elements (typically h1) and then styled using CSS and supporting technologies such as XBL.

When authors use the canvas element, they must also provide content that, when presented to the user, conveys essentially the same function or purpose as the bitmap canvas. This content may be placed as content of the canvas element. The contents of the canvas element, if any, are the element's fallback content.

In interactive visual media, if scripting is enabled for the canvas element, and if support for canvas elements has been enabled, the canvas element represents embedded content consisting of a dynamically created image.

In non-interactive, static, visual media, if the canvas element has been previously painted on (e.g. if the page was viewed in an interactive visual medium and is now being printed, or if some script that ran during the page layout process painted on the element), then the canvas element represents embedded content with the current image and size. Otherwise, the element represents its fallback content instead.

In non-visual media, and in visual media if scripting is disabled for the canvas element or if support for canvas elements has been disabled, the canvas element represents its fallback content instead.

When a canvas element represents embedded content, the user can still focus descendants of the canvas element (in the fallback content). This allows authors to make an interactive canvas keyboard-focusable: authors should have a one-to-one mapping of interactive regions to focusable elements in the fallback content.

The canvas element has two attributes to control the size of the coordinate space: width and height. These attributes, when specified, must have values that are valid non-negative integers. The rules for parsing non-negative integers must be used to obtain their numeric values. If an attribute is missing, or if parsing its value returns an error, then the default value must be used instead. The width attribute defaults to 300, and the height attribute defaults to 150.

The intrinsic dimensions of the canvas element equal the size of the coordinate space, with the numbers interpreted in CSS pixels. However, the element can be sized arbitrarily by a style sheet. During rendering, the image is scaled to fit this layout size.

The size of the coordinate space does not necessarily represent the size of the actual bitmap that the user agent will use internally or during rendering. On high-definition displays, for instance, the user agent may internally use a bitmap with two device pixels per unit in the coordinate space, so that the rendering remains at high quality throughout.

When the canvas element is created, and subsequently whenever the width and height attributes are set (whether to a new value or to the previous value), the bitmap and any associated contexts must be cleared back to their initial state and reinitialized with the newly specified coordinate space dimensions.

When the canvas is initialized, its bitmap must be cleared to transparent black.

The width and height IDL attributes must reflect the respective content attributes of the same name.

Only one square appears to be drawn in the following example:

  // canvas is a reference to a <canvas> element
  var context = canvas.getContext('2d');
  context.fillRect(0,0,50,50);
  canvas.setAttribute('width', '300'); // clears the canvas
  context.fillRect(0,100,50,50);
  canvas.width = canvas.width; // clears the canvas
  context.fillRect(100,0,50,50); // only this square remains

To draw on the canvas, authors must first obtain a reference to a context using the getContext(contextId) method of the canvas element.

context = canvas . getContext(contextId)

Returns an object that exposes an API for drawing on the canvas.

Returns null if the given context ID is not supported.

Contexts are defined by other specifications.

Vendors may also define experimental contexts using the syntax vendorname-context, for example, moz-3d.

When the UA is passed an empty string or a string specifying a context that it does not support, then it must return null. String comparisons must be case-sensitive.


url = canvas . toDataURL( [ type, ... ])

Returns a data: URL for the image in the canvas.

The first argument, if provided, controls the type of the image to be returned (e.g. PNG or JPEG). The default is image/png; that type is also used if the given type isn't supported. The other arguments are specific to the type, and control the way that the image is generated, as given in the table below.

The toDataURL() method must, when called with no arguments, return a data: URL containing a representation of the image as a PNG file. [PNG]

If the canvas has no pixels (i.e. either its horizontal dimension or its vertical dimension is zero) then the method must return the string "data:,". (This is the shortest data: URL; it represents the empty string in a text/plain resource.)

When the toDataURL(type) method is called with one or more arguments, it must return a data: URL containing a representation of the image in the format given by type. The possible values are MIME types with no parameters, for example image/png, image/jpeg, or even maybe image/svg+xml if the implementation actually keeps enough information to reliably render an SVG image from the canvas.

For image types that do not support an alpha channel, the image must be composited onto a solid black background using the source-over operator, and the resulting image must be the one used to create the data: URL.

Only support for image/png is required. User agents may support other types. If the user agent does not support the requested type, it must return the image using the PNG format.

User agents must convert the provided type to ASCII lowercase before establishing if they support that type and before creating the data: URL.

When trying to use types other than image/png, authors can check if the image was really returned in the requested format by checking to see if the returned string starts with one the exact strings "data:image/png," or "data:image/png;". If it does, the image is PNG, and thus the requested type was not supported. (The one exception to this is if the canvas has either no height or no width, in which case the result might simply be "data:,".)

If the method is invoked with the first argument giving a type corresponding to one of the types given in the first column of the following table, and the user agent supports that type, then the subsequent arguments, if any, must be treated as described in the second cell of that row.

Type Other arguments
image/jpeg The second argument, if it is a number between 0.0 and 1.0, must be treated as the desired quality level. If it is not a number or is outside that range, the user agent must use its default value, as if the argument had been omitted.

Other arguments must be ignored and must not cause the user agent to raise an exception. A future version of this specification will probably define other parameters to be passed to toDataURL() to allow authors to more carefully control compression settings, image metadata, etc.

3.8.11.1 Color spaces and color correction

Status: Last call for comments

The canvas APIs must perform color correction at only two points: when rendering images with their own gamma correction and color space information onto the canvas, to convert the image to the color space used by the canvas (e.g. using the 2D Context's drawImage() method with an HTMLImageElement object), and when rendering the actual canvas bitmap to the output device.

Thus, in the 2D context, colors used to draw shapes onto the canvas will exactly match colors obtained through the getImageData() method.

The toDataURL() method must not include color space information in the resource returned. Where the output format allows it, the color of pixels in resources created by toDataURL() must match those returned by the getImageData() method.

In user agents that support CSS, the color space used by a canvas element must match the color space used for processing any colors for that element in CSS.

The gamma correction and color space information of images must be handled in such a way that an image rendered directly using an img element would use the same colors as one painted on a canvas element that is then itself rendered. Furthermore, the rendering of images that have no color correction information (such as those returned by the toDataURL() method) must be rendered with no color correction.

Thus, in the 2D context, calling the drawImage() method to render the output of the toDataURL() method to the canvas, given the appropriate dimensions, has no visible effect.

3.8.11.2 Security with canvas elements

Status: Last call for comments

Information leakage can occur if scripts from one origin can access information (e.g. read pixels) from images from another origin (one that isn't the same).

To mitigate this, canvas elements are defined to have a flag indicating whether they are origin-clean. All canvas elements must start with their origin-clean set to true. The flag must be set to false if any of the following actions occur:

Whenever the toDataURL() method of a canvas element whose origin-clean flag is set to false is called, the method must raise a SECURITY_ERR exception.

Whenever the getImageData() method of the 2D context of a canvas element whose origin-clean flag is set to false is called with otherwise correct arguments, the method must raise a SECURITY_ERR exception.

Even resetting the canvas state by changing its width or height attributes doesn't reset the origin-clean flag.

3.8.12 The map element

Status: Last call for comments

Categories
Flow content.
When the element only contains phrasing content: phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Transparent.
Content attributes:
Global attributes
name
DOM interface:
interface HTMLMapElement : HTMLElement {
           attribute DOMString name;
  readonly attribute HTMLCollection areas;
  readonly attribute HTMLCollection images;
};

The map element, in conjunction with any area element descendants, defines an image map. The element represents its children.

The name attribute gives the map a name so that it can be referenced. The attribute must be present and must have a non-empty value with no space characters. The value of the name attribute must not be a compatibility-caseless match for the value of the name attribute of another map element in the same document. If the id attribute is also specified, both attributes must have the same value.

map . areas

Returns an HTMLCollection of the area elements in the map.

map . images

Returns an HTMLCollection of the img and object elements that use the map.

The areas attribute must return an HTMLCollection rooted at the map element, whose filter matches only area elements.

The images attribute must return an HTMLCollection rooted at the Document node, whose filter matches only img and object elements that are associated with this map element according to the image map processing model.

The IDL attribute name must reflect the content attribute of the same name.

3.8.13 The area element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected, but only if there is a map element ancestor.
Content model:
Empty.
Content attributes:
Global attributes
alt
coords
shape
href
target
ping
rel
media
hreflang
type
DOM interface:
interface HTMLAreaElement : HTMLElement {
           attribute DOMString alt;
           attribute DOMString coords;
           attribute DOMString shape;
  stringifier attribute DOMString href;
           attribute DOMString target;
           attribute DOMString ping;
           attribute DOMString rel;
  readonly attribute DOMTokenList relList;
           attribute DOMString media;
           attribute DOMString hreflang;
           attribute DOMString type;

  // URL decomposition IDL attributes
           attribute DOMString protocol;
           attribute DOMString host;
           attribute DOMString hostname;
           attribute DOMString port;
           attribute DOMString pathname;
           attribute DOMString search;
           attribute DOMString hash;
};

The area element represents either a hyperlink with some text and a corresponding area on an image map, or a dead area on an image map.

If the area element has an href attribute, then the area element represents a hyperlink. In this case, the alt attribute must be present. It specifies the text of the hyperlink. Its value must be text that, when presented with the texts specified for the other hyperlinks of the image map, and with the alternative text of the image, but without the image itself, provides the user with the same kind of choice as the hyperlink would when used without its text but with its shape applied to the image. The alt attribute may be left blank if there is another area element in the same image map that points to the same resource and has a non-blank alt attribute.

If the area element has no href attribute, then the area represented by the element cannot be selected, and the alt attribute must be omitted.

In both cases, the shape and coords attributes specify the area.

The shape attribute is an enumerated attribute. The following table lists the keywords defined for this attribute. The states given in the first cell of the rows with keywords give the states to which those keywords map. Some of the keywords are non-conforming, as noted in the last column.

State Keywords Notes
Circle state circle
circ Non-conforming
Default state default
Polygon state poly
polygon Non-conforming
Rectangle state rect
rectangle Non-conforming

The attribute may be omitted. The missing value default is the rectangle state.

The coords attribute must, if specified, contain a valid list of integers. This attribute gives the coordinates for the shape described by the shape attribute. The processing for this attribute is described as part of the image map processing model.

In the circle state, area elements must have a coords attribute present, with three integers, the last of which must be non-negative. The first integer must be the distance in CSS pixels from the left edge of the image to the center of the circle, the second integer must be the distance in CSS pixels from the top edge of the image to the center of the circle, and the third integer must be the radius of the circle, again in CSS pixels.

In the default state state, area elements must not have a coords attribute. (The area is the whole image.)

In the polygon state, area elements must have a coords attribute with at least six integers, and the number of integers must be even. Each pair of integers must represent a coordinate given as the distances from the left and the top of the image in CSS pixels respectively, and all the coordinates together must represent the points of the polygon, in order.

In the rectangle state, area elements must have a coords attribute with exactly four integers, the first of which must be less than the third, and the second of which must be less than the fourth. The four points must represent, respectively, the distance from the left edge of the image to the left side of the rectangle, the distance from the top edge to the top side, the distance from the left edge to the right side, and the distance from the top edge to the bottom side, all in CSS pixels.

When user agents allow users to follow hyperlinks created using the area element, as described in the next section, the href, target and ping attributes decide how the link is followed. The rel, media, hreflang, and type attributes may be used to indicate to the user the likely nature of the target resource before the user follows the link.

The target, ping, rel, media, hreflang, and type attributes must be omitted if the href attribute is not present.

The activation behavior of area elements is to run the following steps:

  1. If the DOMActivate event in question is not