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Re: What is the advantage of RELAX in comparison to Schemas?

• From: ht@c... (Henry S. Thompson)
• To: Bob Kline <bkline@r...>
• Date: Fri, 02 Mar 2001 20:37:19 +0000

Bob Kline <bkline@r...> writes:

> On Tue, 30 Jan 2001, Inga Eckermann wrote:
> 
> > Hello,
> > 
> > I am new to this list and have read about you mentioning RELAX and
> > TRX. Why do I need these standards? On the RELAX-webpage is written:
> > 
> > Compared with DTD(Document Type Definition), RELAX has new features:
> > 
> >              RELAX grammars are represented in the XML instance syntax 
> >              RELAX borrows rich datatypes of XML Schema Part 2 
> >              RELAX is namespace-aware 
> > 
> > Is it not all included in Schemas as well?
> 
> The most significant difference (from our point of view, at any rate)
> between RELAX and W3C's Schema spec is that the former supports
> context-sensitive content models.  Schematron also supports this
> essential feature, which allows you to specify that a certain type of
> content is allowed for a given element only if the element's parent is
> <X>..</X>, 

This _is_ supported by W3C XML Schema.  It's called local element
declarations.

> or only if the element contains a certain attribute with a
> specific value.  Very disappointing that W3C decided to leave this out.

W3C XML Schema doesn't support this, true.  I'm not a RELAX expert,
but I don't it does either.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2001, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@c...
		     URL: http://www.ltg.ed.ac.uk/~ht/

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