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Implementations/Non-Implementations of xs:redefine?

From: Eliot Kimber <ekimber@reallysi.com>
Date: Wed, 19 Dec 2007 10:18:42 -0600
Message-ID: <47694462.4020308@reallysi.com>
To: xmlschema-dev@w3.org

I'm trying to get a clear understanding of what the current and likely 
future state of implementation of the xs:redefine feature is.

I understand from reviewing the message traffic here and elsewhere that 
the spec is (possibly) ambiguous in XSD 1.0 on how redefine should be 
correctly processed (or what its precise result is) and that there is 
intent to clarify that in XSD 1.1.

However, my (limited) understanding is that, because of the inherent 
requirement by xs:redefine to do lazy evaluation of schema components to 
determine their effective value, some schema-supporting tools may never 
implement redefine.

Is that understanding correct? If so, is there a known list of such tools?

If that understanding is not correct I'd like to know that too.

The immediate issue for me is whether or not it is practical and/or wise 
to use XSD schemas for DITA specializations in advance of implementation 
of something like Mike Kay's proposed xs:override feature. I have 
clients who feel schemas are a better choice generally (which I would 
otherwise agree with wholeheartedly) and I need to advise them correctly 
on the suitability or non-suitability of schemas for DITA.

I already know that the xs:redefine feature cannot perform the sorts of 
overrides outlined in Mike's xs:override proposal, which would be 
sufficient for me to recommend against schemas for DITA at this time.

But...if all the important tools will implement redefine in a way that 
allows at least extension of base models then it would at least be 
practical to use schemas for DITA where the inability to disallow base 
element types would not be a deal breaker.


Eliot Kimber
Senior Solutions Architect
"Bringing Strategy, Content, and Technology Together"
Main: 610.631.6770
Received on Thursday, 20 December 2007 03:40:00 UTC

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