Paul Grosso. <a href="http://www.w3.org/TR/2003/WD-xsl11-req-20031217"><cite>Extensible Stylesheet Language (XSL) Version 1.1 Requirements.</cite></a> 17 December 2003. W3C Working Draft. (Work in progress.) URL: <a href="http://www.w3.org/TR/2003/WD-xsl11-req-20031217">http://www.w3.org/TR/2003/WD-xsl11-req-20031217</a>