2.2.2 [W3C-XSLT] Section 2.1, XSLT Namespace

C0024:

The specification states:

 XSLT processors must use the XML namespaces mechanism [XML Names] to recognize 
 elements and attributes from this namespace. Elements from the XSLT namespace 
 are recognized only in the stylesheet not in the source document. The complete 
 list of XSLT-defined elements is specified in [B Element Syntax Summary].

MSXML6

Only Instruction elements from the complete list of XSLT-defined elements specified in Appendix B of [W3C-XSLT] are recognized.