2.2.2 [NamespacesXML1.1] Section 5, Using Qualified Names


The specification states:

 Note that DTD-based validation is not namespace-aware in the following sense: 
 a DTD constrains the elements and attributes that may appear in a document 
 by their uninterpreted names, not by (namespace name, local name) pairs.

IE9 Mode (All Versions)

Validation by using DTDs is not performed.