Problems validating the W3C schema DTD's

Andrew Layman andrewl at
Mon May 17 20:39:45 BST 1999

Brant Dainow wrote, regarding Microsoft's MSXML parser, "It spits an error
that attribute 'xlmns' must be type #FIXED.  Any comments?"

The MSXML parser requires that any "xmlns" attribute declared in a DTD must
be FIXED because, if you want to use the DTD to validate an instance, you
must use exactly the same prefixes in the instance as were used in the DTD.

Looking at the same point from another angle, DTDs do not treat namespace
prefixes as symbolic intermediaries, but instead as ordinary characters in
element and attribute names.  As such, their binding is fixed by the author
of the DTD, and any alteration of the binding in a document instance would
produce an instance no longer described by that DTD. 

Presumably the work now underway in the W3C XML Schemas Activity will loosen
this restriction.

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