2.2.6 [W3C-XSLT] Section 7.1.2, Creating Elements with xsl : element

C0005:

The specification states:

 The name attribute is interpreted as an attribute value template. It is an error if
 the string that results from instantiating the attribute value template is not a 
 QName. An XSLT processor may signal the error; if it does not signal the error,
 then it must recover by making the result of instantiating the xsl:element 
 element be the sequence of nodes created by instantiating the content of the 
 xsl:element element, excluding any initial attribute nodes.

MSXML3 and MSXML6

An error is signaled when the string that results from instantiating the attribute value template is not a QName.