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Re: Impact of the usage of unique identifier as URN into XML document s ?

From: Henry S. Thompson <ht@inf.ed.ac.uk>
Date: Mon, 15 Mar 2004 15:18:06 +0000
To: Hess Yvan <yvan.hess@imtf.ch>
Cc: "'xmlschema-dev@w3.org'" <xmlschema-dev@w3.org>
Message-ID: <f5bbrmygmvl.fsf@erasmus.inf.ed.ac.uk>

Hess Yvan <yvan.hess@imtf.ch> writes:

> <xs:key name="DocIdentifier">
>   <xs:selector xpath="."/> 
>   <xs:field xpath="@id"/>
> </xs:key>

This does not have the desired effect, it will always be true, as
there is only ever one id attribute on a 'document' element.  To have
this do useful work, you need to change it to

<xs:key name="DocIdentifier">
   <xs:selector xpath=".//my:document"/> 
   <xs:field xpath="@id"/>
</xs:key>

and move it to within an element declaration for an element which
scopes all your 'document' nodes.

> It works fine, but I don't know the future impacts/limitation of such
> choice, specially concerning the usage of URN as unique identifier in
> conjunction with others XML technologies. Does anybody have any comments,
> suggestions or best practices about this subject? Can you see future
> limitation?

I don't foresee any future problems with this -- the actual _type_ of
the attribute you call 'id' is completely within your control.

ht
-- 
 Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
                     Half-time member of W3C Team
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            Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
                   URL: http://www.ltg.ed.ac.uk/~ht/
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Received on Monday, 15 March 2004 10:18:38 UTC

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