eXtensible Stylesheet Language (XSL), Version 1.0 - (W3C Recommendation) an XSL stylesheet specifies the presentation of a class of XML documents by describing how an instance of the class is transformed into an XML document that uses the formatting vocabulary
XSL Requirements Summary - (W3C Working Draft as of 2001-09-03) list of requirements considered to be in scope for XSL in general with no reference to timing or target version