#11 XSLT uses "xsl:" prefix not namespace

[Richard Light]

XSLT processing will fail if the stylesheet has the
correct XSLT namespace URI
("http://www.w3.org/1999/XSL/Transform") but uses a
prefix other than "xsl:" to refer to this namespace.

This assumption is built into the code, which has a
constant:

XpsXSLColon = 'xsl:';

that is used in eight places as a test for "XSLT" syntax.