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Re: Clarification of "Element Declarations Consistent"

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: Thu, 30 Oct 2003 09:05:20 +0000
To: "David Bau" <david.bau@bea.com>
Cc: <www-xml-schema-comments@w3.org>
Message-ID: <f5bptgft7sf.fsf@erasmus.inf.ed.ac.uk>

"David Bau" <david.bau@bea.com> writes:

> Hello all, a question about the Element Declarations
> Consistent rule.
>
> The Element Declarations Consistent rule for model groups
> (http://www.w3.org/TR/xmlschema-1/#cos-element-consistent)
> rules out inconsistent element declarations like the
> following two conflicting definitions of element <a>,
> i.e., <a> cannot be both an "int" and a "string" in
> the same group:
>
> (example-1)
> <xs:complexType name="example-1">
>   <xs:sequence>
>     <xs:element name="a" type="xs:int"/>
>     <xs:element name="whatever"/>
>     <xs:element name="a" type="xs:string"/>
>   </xs:sequence>
> </xs:complexType>
>
> In addition to explicit element declarations, the rule
> also prevents conflicts between elements that appear
> "either directly, indirectly, or implicitly", i.e., between
> nested model groups or elements permitted via
> substitution groups.
>
> My question: consider the following "tricky" indirect case
> involving a wildcard referencing a global element -
>
> (example-2)
> <xs:element name="a" type="xs:string"/>
> <xs:complexType name="example-2">
>   <xs:sequence>
>     <xs:element name="a" type="xs:int"/>
>     <xs:element name="whatever"/>
>     <xs:any namespace="##targetNamespace" processContents="lax"/>
>   </xs:sequence>
> </xs:complexType>
>
> Clearly the local <a> and the indirect reference to the
> global <a> are "inconsistent" with each other within the
> content model of example-2, but I'm not sure if the
> "directly, indirectly, or implicitly" language in the
> ETC rule captures this case.
>
> Is there a hole in the EDC rule language with respect to
> example-2? Is this something that could be clarified in
> an errata?

Yes and yes, in my opinion.

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 Thursday, 30 October 2003 04:06:15 UTC

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