For one example, the new per-LABEL TEXT attribute is not supported in either the XSD or XSL. XSD also shows a version of 6.0.1 in the 6.2.x tarballs.
assigning to @aboudreault
Added per-label TEXT attribute in xml schema and xsl (closes #4639)
If you notice any missing feature in xml stuff... please open another issue and mention them in the description.