ID value space

Hmmm... regarding the syntax of ID:

  XML 1.0 says "...must match the Name production."
  http://www.w3.org/TR/REC-xml#id

  XSD Part 2 says "...set of all strings that match the NCName production..."
  http://www.w3.org/TR/xmlschema-2/#ID

Why the difference?  Is this a difference of opinion between the designers
of XML1+ and the designers of W3 Schema, or is there a technical reason?

Thanks,
Chris  

___________________________________________
Chris Wilper                                                    
Cornell Digital Library Research Group
http://www.cs.cornell.edu/~cwilper/