Associating Style Sheets with XML documents Version 1.0 - W3C specification that allows a style sheet to be associated with an XML document by including one or more processing instructions with a target of xml-stylesheet in the document's prolog. (W3C Recommendation 29 June 1999) - http://www.w3.org/TR/xml-stylesheet/
XML Script - XML Script is an alternative to XSL that claims to be simpler to use for data transformation tasks. - http://www.xmlscript.org/