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RE: CURIEs vs. QNames

From: Laurent Le Meur <laurent.lemeur@afp.com>
Date: Sun, 6 Nov 2005 22:53:07 +0100
Message-Id: <200511062152.jA6LqQSm010851@alox.afp.com>
To: "'Norman Walsh'" <Norman.Walsh@Sun.COM>, "'Mark Birbeck'" <mark.birbeck@x-port.net>
Cc: "'Henry S. Thompson'" <ht@inf.ed.ac.uk>, <public-rdf-in-xhtml-tf@w3.org>

Hi Norman,
> 
> My concern is that you seem to be introducing a new way to define
> something that is lexically indistinguishable from and conceptually
> similar to a QName that may appear in contexts where QNames may
> appear.
 
CURIEs are lexically different from QNames:

With "cat" defined as "http://iptc.org/category/" (it's an example),
consider:  <iptc:subject code="cat:15000000" />

"cat:15000000", after being expanded to "http://iptc.org/category/15000000",
could unambiguously identify the concept "Sport".

But this is not a valid QName, and for good reason: nobody would use this
concept identifier as an element or attribute name (which is the rationale
behind the creation of namespaces and QNames).

> If there is any context in which this fragment could appear
> 
>    <any:Vocab xmlns:p="http://example.org/">
>      <html:xxx someAttribute="p:lname"/>
>    </any:Vocab>
> 
> and the interpretation of p:lname would not be the tuple
> (http://example.org/,lname), I think that's a real problem.
> 

It must be clear that - at least in the IPTC specs - a QName (i.e., logically,
the abbreviation of an element of or attribute name) will not appear where a
CURIE (i.e. the abbreviation of a concept identifier) should.

So there will be no confusion about the interpretation of a CURIE, and the way
it should be expanded. 

Note: Our concern about the use of xmlns as a way to map the CURIE prefix to its
associated URI is based on this need for compactness in the news industry, when
many schemes are used simultaneously. 

It seems that XPath 1.0 functions spec [1], which explicitly uses QNames, does
not make namespace declarations mandatory neither (or do I miss something?).

[1] <http://www.w3.org/TR/xpath-functions/>

Laurent Le Meur
AFP, Medialab manager
IPTC, News Architecture WP Chair
 



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Received on Sunday, 6 November 2005 21:52:47 GMT

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