The namespace name http://www.w3.org/1999/XSL/Transform
identifies elements which serve as instructions in the XSLT language.
The XSLT language has two versions which are distinguished by content of the
version attribute:
A Working Draft of version 2.1 of the language, currently in development, is available at XSL Transformations (XSLT) Version 2.1. This will be renumbered 3.0 for the next publication.
xsl-list, public mailing list for discussing XSLT