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RE: Enlightenment via avoiding the T-word

• From: "Fuchs, Matthew" <matthew.fuchs@c...>
• To: Ronald Bourret <rpbourret@r...>, xml-dev@l...
• Date: Wed, 29 Aug 2001 11:12:47 -0700

If the mapping from local element names in a schema to ulabels was
one-to-one, and we had the mechanisms in the document to express those
names, as I suggest in my previous email (from Monday), then one would not
need the full PSVI to get all the ulabels - one could actually express them
in the document, just as we do now with "regular" namespaces.  This is
partly due to the insufficient support for local types.

Regarding validation vs. typing, validation is a kind of type-checking
(constraints do specify types, just not all the types are named).  However,
in validation, you only ask if the document was correct, and don't get to
find out what the types were.

Matthew

> -----Original Message-----
> From: Ronald Bourret [mailto:rpbourret@r...]
> Sent: Monday, August 27, 2001 11:21 PM
> To: xml-dev@l...
> Subject: Re: Enlightenment via avoiding the T-word
> 
> 
> "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.
> 
> <minor_annoyance_and_aside>
> 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" :)
> </minor_annoyance_and_aside>
> 
> -- Ron
> 
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