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Re: Enlightenment via avoiding the T-word
- From: Ronald Bourret <email@example.com>
- To: firstname.lastname@example.org
- Date: Mon, 27 Aug 2001 23:21:09 -0700
"Fuchs, Matthew" wrote:
> DTDs provide a mapping from well formed documents into, essentially, a term
> algebra for a particular set of structures.
So far so good.
> I.e., once you've validated a
> document, any element structure (but, alas, not attributes - but at least
> there's only one level of nesting) with a particular label is of the set of
> structures "labeled" by an element definition with the same label. Of
> course, as you've pointed out, this is only one piece of the semantics, the
> "label->meaning" map, but it's the piece validition provides.
Mapping elements/attribute to t&*&%s is not validation, since validation
includes things above and beyond this mapping, such as checking that
IDREF values point to actual IDs and that IDs are unique.
In other words, it is not necessary to generate the complete PSVI or to
validate a document to do this mapping. Unfortunately, the PSVI is
defined in these terms, rather than having separate layers, a mapping
layer and a constraint checking layer.
And, yes, I finally did understand what Elliotte Rusty Harold was
talking about when he said, "W3C XML Schema Language confuses the two
separate issues of typing and constraints checking" :)