Metadata is structured data about data.
In the computing industry, there are ongoing standardization efforts towards metadata with the goal of promoting industry interoperability and efficiency. Content creators should track these developments and include appropriate metadata in their SVG content which conforms to these various metadata standards as they emerge.
The W3C has a Semantic Web Activity which has been established to serve a leadership role, in both the design of enabling specifications and the open, collaborative development of technologies that support the automation, integration and reuse of data across various applications. The Semantic Web Activity builds upon the earlier W3C Metadata Activity, including the definition of Resource Description Framework (RDF). The set of six specifications for RDF can be found starting Resource Description Framework Primer [RDF]
Another activity relevant to most applications of metadata is the Dublin Core [DCORE], which is a set of generally applicable core metadata properties (e.g., Title, Creator/Author, Subject, Description, etc.).
Individual industries or individual content creators are free to define their own metadata schema but are encouraged to follow existing metadata standards and use standard metadata schema wherever possible to promote interchange and interoperability. If a particular standard metadata schema does not meet your needs, then it is usually better to define an additional metadata schema in an existing framework such as RDF and to use custom metadata schema in combination with standard metadata schema, rather than totally ignore the standard schema.
Metadata which is included with SVG content should be specified within 'metadata' elements. The contents of the 'metadata' should be elements from other XML namespaces, with these elements from these namespaces expressed in a manner conforming with either the "Namespaces in XML 1.0" or "Namespaces in XML 1.1" Recommendations [XML-NS10][XML-NS].
Authors should provide a 'metadata' child element to the 'svg' element within a stand-alone SVG document. The 'metadata' child element to an 'svg' element serves the purposes of identifying document-level metadata.
<define name='metadata'>
<element name='metadata'>
<ref name='DTM.AT'/>
<ref name='DTM.CM'/>
</element>
</define>
Here is an example of how metadata can be included in an SVG document. The example uses the Dublin Core version 1.1 schema. (Other XML-compatible metadata languages, including ones not based on RDF, can be used also.)
<?xml version="1.0"?>
<svg width="4in" height="3in" version="1.2" baseProfile="tiny"
xmlns = 'http://www.w3.org/2000/svg'>
<desc xmlns:foo="http://example.org/foo">
<foo:title>This is a financial report</foo:title>
<foo:descr>The global description uses markup from the
<foo:emph>foo</foo:emph> namespace.</foo:descr>
<foo:scene><foo:what>widget $growth</foo:what>
<foo:contains>$three $graph-bar</foo:contains>
<foo:when>1998 $through 2000</foo:when> </foo:scene>
</desc>
<metadata>
<rdf:RDF
xmlns:rdf = "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:rdfs = "http://www.w3.org/2000/01/rdf-schema#"
xmlns:dc = "http://purl.org/dc/elements/1.1/" >
<rdf:Description about="http://example.org/foo"
dc:title="Foo Financial Report"
dc:description="$three $bar $thousands $dollars $from 1998 $through 2000"
dc:publisher="Example Organization"
dc:date="2000-04-11"
dc:format="image/svg+xml"
dc:language="en" >
<dc:creator>
<rdf:Bag>
<rdf:li>Irving Bird</rdf:li>
<rdf:li>Mary Lambert</rdf:li>
</rdf:Bag>
</dc:creator>
</rdf:Description>
</rdf:RDF>
</metadata>
</svg>