Namespaces hate validation!

John Cowan cowan at
Wed Jan 6 22:33:53 GMT 1999

Murray Maloney wrote:

> Thus validation depends on the existence of a namespace-aware
> processor that can rewrite an XML document as an equivalent
> document with all namespaces declared on the root element
> and with no use of default namespaces or local scoping
> of prefixes.
> And, that processor is undefined and unimplemented.

I suppose eventually someone will have to MOV MOUTH, MONEY.
But not me, not yet.
> Oh, by the way, what do you do about any entities you encounter?
> I mean, when I combine an HTML DTD with a graveyard DTD,
> how do I avoid name collision between general text entities?
>         agrave, egrave, igrave, ograve, ugrave
> Now I assume that you will tell me that there is a *simple*
> algorithm for transforming the DTD and/or the instance to
> deal with name collisions.

Now don't mix up two different issues!  There is *no* algorithm,
and nobody claims there is, for merging DTDs automatically!
Tim thinks one will eventually be found, about which *I* am
deeply skeptical.

The claim being made here is:


	1) a mixed-namespace DTD, and
	2) a mixed-namespace instance
		(which is WF and namespace-compliant)
		that purports to conform to it, and
	3) a source of information
		about the prefix-to-URI map(s) being used in the DTD,

	it is possible by preprocessing

	1) the DTD (without the instance, and
	2) the instance (without the DTD)

	to produce a modified (DTD, instance) pair which will validate
		using an ordinary XML validator

	if and only if

	the original (DTD, instance) pair would validate
		using a (nonexistent) namespace-aware validator,

	and the resulting modified instance
		will be namespace-equivalent to the original instance.

John Cowan		cowan at
	You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
	You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
		Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)

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