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Re: use="prohibited"

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: Tue, 08 Jul 2003 09:09:50 +0100
To: "Daplyn, Tim" <Tim.Daplyn@eu.sony.com> (by way of "C. M. Sperberg-McQueen" <cmsmcq@acm.org>)
Cc: W3C XML Schema Comments list <www-xml-schema-comments@w3.org>
Message-ID: <f5bllv9wib5.fsf@erasmus.inf.ed.ac.uk>

"Daplyn, Tim" <Tim.Daplyn@eu.sony.com> (by way of "C. M. Sperberg-McQueen" <cmsmcq@acm.org>) writes:

> The recommendation includes a number of attribute declarations within
> <restriction>s which have only 'name' and 'use' defined e.g.
>
> 	<xs:attribute name="form" use="prohibited"/>
> 	(in definition of topLevelAttribute)
>
> Xerces seems to fail this type of redefinition with the following error:
>
>    Message: Type of attribute {0} must be validly derived from type of
> attribute in base
>
> This seems to be based on the constraints section
> http://www.w3.org/TR/xmlschema-1/#derivation-ok-restriction
>
> Please does anyone have a definitive answer as to whether the following xml
> is valid or not?
>
> 	<complexType name="typeB">
> 		<attribute name="attr" type="string" use="optional"/>
> 	</complexType>
> 	<complexType name="typeR">
> 		<complexContent>
> 			<restriction base="typeB">
> 				<attribute name="attr" use="prohibited"/>
> 				<!-- Do we _have_ to specify 'type' again?
> -->
> 			</restriction>
> 		</complexContent>
> 	</complexType>

It's valid.  The valid derivation constraint cited by Xerces is on
schema _components_, but as the REC says in several places, an xml
element of the form <xs:attribute name="..." use="prohibited"/>
corresponds to no component at all.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
                      Half-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/
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Received on Tuesday, 8 July 2003 04:09:52 UTC

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