Namespace handling in XML Processors

[schen at falconwing.com]

Speaking of namespaces,

It's very confusing as to what is regarded as correct behavior by XML
processors when encountering a document with namespaces.
All the standard seems to do is to allow use of the same element names
without conflict.

As has been stated in the thread [Fwd: ATTN: Please comment on XHTML
(before it's too late)], namespaces are explicitly not defined to be
either schemas or DTDs, although the standard doesn't preclude it either.

So two questions:

1) If an XML processor was semantically interpreting an XML document but
encounters an unknown namespace, is it mandated to ignore all elements and
attributes in that namespace?  I thought this was the case, but after
re-reading the standard I see it's not defined.  If this is not
standardized, can anyone say what is currently the common practice?

2) How should a validating XML parser deal with namespaces?  This doesn't
seem to be defined very clearly.  I can see that we can include namespace
declarations in the DTD external and internal subsets, so I guess that if
I have a document mixing two namespaces I would have the external DTD
point to the one for the "primary" namespace and then use the internal
subset to override the external DTD to provide for insertion of elements
and attributes using the second namespace.  But this can rapidly get out
of hand with mixing of even more namespaces.  Is there any better
mechanism for this, or are any planned?  

. . . Sean.



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