ns 1.1

This feels like a dumb question, but I am not clear on an issue.Section 
7 of Namespaces in XML 1.1 reads:

"This specification applies to XML 1.1 documents. To conform to this 
specification, a document /MUST/ be well-formed according to the XML 1.1 
specification." [1]

Namespaces 1.1 supports xmlns="". Can I undeclare a namespace in an XML 
1.0 document or must it be an XML 1.1 document? Or does it simply depend 
on the processor?

Mike

[1] http://www.w3.org/TR/2004/REC-xml-names11-20040204/#Conformance