VBXML.com has created conformance reports for Microsoft's XSLT implementation and its XPath support.

Teun Duynstee has built tables that identify support for the W3C specifications in the version of MSXML that shipped with Internet Explorer 5, along with MSXML 2.6 (January 2000 preview) and MSXML 3.0 (both the March and May previews).

The W3C specs are treated as the primary point of reference for conformance, making this most useful to developers who need to create XSLT that works with the W3C version of XSLT on multiple platforms, rather than users of older versions of MSXML who are updating their code. (Since the new MSXML continues to support the older XSLT using the old namespace this may not be as pressing a problem.)