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RE: Are we losing out because of grammars?
- From: "Bullard, Claude L (Len)" <email@example.com>
- To: firstname.lastname@example.org
- Date: Thu, 01 Feb 2001 09:02:52 -0600
Ummm... so far it looks like they have about
the same expressive power. Can you show
examples where they don't? Appreciated...
One is sometimes struggling against the legacy,
actually "the rules of now". For example, SGML
exclusions and inclusions were used because
the thing being modeled was itself, a document
that a modeler might consider irrational on
the surface. Later, one found that the process
or route of the document made that a requirement.
One might have broken up the DTDs into multiple
DTDs appropriate to different steps (and in very
many cases should have; that was a political
problem), but then one had to state authoritatively
that these were different documents and sometimes, one
was not allowed to redefine the artifacts that
way. Thus, we ended up with the ungainly but
workable "switch DTDs" with ORs at the top
level and occasionally scattered throughout
to maintain wrapper tags.
It isn't simply rules vs grammar. That is too
easy an assumption. It is also a problem
of matching means to process and process
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From: Rick Jelliffe [mailto:email@example.com]
Smart readers of XML-DEV will of course say "oh, but probably you can
express things in
content models that you cannot express in paths and rules" but I have my
doubts: a really complex content model is IMHO often (always) either the
sign of struggling against the grammar or a kind of tag ommission: if there
is some complex structure there, why isn't it explicitly labelled for all
the world to see?