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RE: clarification of redefine semantics

From: Michael Kay <mike@saxonica.com>
Date: Sat, 12 Feb 2005 09:57:13 -0000
To: "'James Taylor'" <JTaylor@nextance.com>, <xmlschema-dev@w3.org>
Message-Id: <E1Czu1h-0007N8-00@ukmail1.eechost.net>
 
 >  My reading of Schema 1.0 is that it's absolutely unambiguous that if the
combined schema is accepted at all, the redefinition of Address   is
pervasive and applies throughout the schema that results from the transitive
closure of the files referenced from Company.xsd. 
 
The thing that's hopelessly inadequate in the current specs is that they
suggest that you should process each schema document, derive a set of schema
components, and then assemble the components as required by
import/include/redefine. The fact is, you can't do that, because for example
you can't decide what data type a fixed or default value is until all the
components are available: which means you need to keep the original lexical
value (and its namespace context, just in case it turns out to be a QName)
until everything is known (if indeed there *is* a time when everything is
known!). There are other examples of this, for example the effect of
xs:redefine depends on whether the XML representation specifies
form="qualified", which is information that's only available in the XML
representation and not in the component model.
 
So there's no way one can say the current specs are unambiguous in this
area.
 
Michael Kay
http://www.saxonica.com/
 
Received on Saturday, 12 February 2005 09:57:24 GMT

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