RE: [xml-dev] Element equivalence under XML Namespaces

["Michael Kay" <mike@saxonica.com>]

> Would any XML/Namespaces guru be willing to answer the 
> following question for me?  Is the following a well-formed 
> XML document:
> 
> <?xml version="1.0"?>
> <doc xmlns="http://foo.com/foo";>
>    <foo:elem xmlns:foo="http://foo.com/foo";>
>    </elem>
> </doc>
> 

No, it's not. Well-formedness is defined in the XML specification, and this
doesn't know anything about namespaces; tags must therefore match lexically
rather than semantically. The XML Namespaces recommendation is layered on
top of XML, attaching special semantics to attributes whose names start with
xmlns and to names that contain a colon. 

Technically there is a class of documents that conform to the XML
specification but not to the XML Namespaces specification. No-one is very
interested in such documents nowadays (you can't process them with XSLT, for
example) but some specifications such as DOM still support them and most XML
parsers are still prepared to parse them. The bottom layer of the XML stack
is not namespace-aware.

Michael Kay
http://www.saxonica.com/