For compatibly reason the fdt:nodeId have to is starting with a letter in all the XML.

This will only be detected by the .NET parser and not by MSXML.

If you get the error message "The 'x-schema:FDTDatatypesSchema.xml:nodeId" attribute has an invalid value according its datatype", you might be wondering why this is an issue.

The nodeId attribute is defined in FDTDataTypesSchema and has datatype ID. Typically you would find out details on XDR datatypes using the Microsoft MSDN information. But there, Microsoft only tells us that the ID must be unique throughout the document.

However, Microsoft actually follows the W3C recommendation when it comes to the ID attribute. In W3C's definition, the ID datatype inherits from NCName. NCName is now defined as starting with a letter.

Links:

http://msdn.microsoft.com/en-us/library/ms256121(VS.85).aspx
http://msdn.microsoft.com/en-us/library/ms256065(v=VS.85).aspx
http://www.w3.org/TR/xmlschema-2/#built-in-datatypes
http://www.w3.org/TR/1999/REC-xml-names-19990114/#NT-NCName