2.2.2 [XML] Section 2.3, Common Syntactic Constructs
The specification states:
Note: The Namespaces in XML Recommendation [XML Names] assigns a meaning to names containing colon characters. Therefore, authors should not use the colon in XML names except for namespace purposes, but XML processors must accept the colon as a name character.
MSXML3 and MSXML6
XML names that begin with a colon (for example, :doc) are not valid.
Specifying a name that begins with a colon results in an error with an error code of
0xC00CE504 and an error reason of "A name was started with an invalid character."