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  • From: Rick JELLIFFE <ricko@g...>
  • To: xml-dev@l...
  • Date: Wed, 02 Aug 2000 16:30:06 +0800

Bob Kline wrote:
> 
> On Wed, 2 Aug 2000, Rick JELLIFFE wrote:
> 
> > RELAX (and DCD) provide something much better: they allow
> > co-occurence constraints. I think these are limited to just element
> > names and attributes along the ancestor axis, so that
> > stream-processing can be done.  Schematron allows constraints from
> > any axis, including poking around other documents. Dave Ragget's
> > Assertion Grammars started the idea AFAIK.

Oops, wrong term, right idea. Not "co-occurrence constraint" (i.e., if
you have x attribute you must have y) but "attributes can help determine
the type of an element".  I apologise for this. So slack.

For capturing many kinds of arbitrary constraints before modeling them,
my schema language schematron is quite useful. 
http://www.ascc.net/xml/resource/schematron/schematron.html
You can make assertions about the structure in a fairly rapid,
incremental way. Then when you move to a schema language with datatyping
(XMl Schemas, RELAX, etc) you can tick off or delete each assertion in
the Schematron schema.

Rick Jelliffe

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