On Fri, 2004-05-28 at 03:04, G. Ken Holman wrote:
> At 2004-05-28 08:12 +0900, MURATA Makoto wrote:
> >Many people think that schemas provide semantics to documents.
>
> I believe schemas are merely syntax checkers at the level of the presence
> of labeled branches in a hierarchical tree.
>
> I believe semantics are implemented solely by applications and how they
> wish to interpret the labelled hierarchy of information. The syntax of the
> semantics is typically prose. People have tried to convince me that the
> use of taxonomies can somehow express semantics formally, but I haven't
> grasped this concept yet.
People have very different assumptions about what "semantics" is and put
the bar at different levels.
Many believe that a first step toward semantics is classification
through indirection and schema languages can provide that level.
The assumption here is that it's easier to attach semantics (whatever
that means and whatever the technology to formalise them might be) to
datatypes or substitution groups than to attach them to elements and
attributes because many elements and attributes will share the same
datatypes or substitution groups.
Being able to get a XSLT transformation match elements on their types or
substitution groups is an example of that idea.
Thus, I wouldn't say that schemas provide semantics and I do agree that
semantics are implemented solely by applications, but in that case
schemas provide a new indirect way to attach the applications that
implement the semantics (the XSLT transformation in my example) to the
labeled branch of the hierarchical tree.
Whether that indirection is useful or not is yet to be seen.
Eric
--
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Upcoming XML schema languages tutorial:
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Eric van der Vlist http://xmlfr.org http://dyomedea.com
(ISO) RELAX NG ISBN:0-596-00421-4 http://oreilly.com/catalog/relax
(W3C) XML Schema ISBN:0-596-00252-1 http://oreilly.com/catalog/xmlschema
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Received on Fri May 28 08:03:06 2004
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