Inappropriate use of XML Namespaces in W3C XML Schema?

In Part 2 of the W3C XML Schema 1.0 Recommendation it is indicated that 
datatypes are contained in designated XML namespaces.

This seems to me to be in conflict with the Namespaces in XML 1.0 
Recommendation which defines an XML namespace as applying to element type names and 
attribute names. There is no provision that I can see in the Namespaces in XML Rec 
for datatype names being part of an "XML namespace".

Correcting this seeming discrepancy should be straightforward but it seems to 
me that it needs to be tidied.

Andrew Watt