W3C home > Mailing lists > Public > public-rdf-in-xhtml-tf@w3.org > January 2009

Re: Validation issue with the xsi namespace

From: Shane McCarron <shane@aptest.com>
Date: Sat, 24 Jan 2009 16:52:00 -0600
Message-ID: <497B9B90.4040308@aptest.com>
To: Christoph LANGE <ch.lange@jacobs-university.de>
CC: Stephane Corlosquet <stephane.corlosquet@deri.org>, public-rdf-in-xhtml-tf@w3.org

Because the are *namespace* URIs, not *vocabulary* URIs.  They were 
never intended to be expanded by concatenating the expanded prefix with 
the value after the colon.  QNames are never concatenated - they are 
treated as a tuple.  CURIEs are ALWAYS concatenated, but CURIE prefixes 
associate a prefix with a string that maps into a vocabulary.  This is 
the essential difference between QNames and CURIEs, at least with regard 
to how they are used in RDFa.

Christoph LANGE wrote:
> On Thursday 22 January 2009 12:59:08 Shane McCarron wrote:
>> It basically has to do with dereferencing the resulting URI when you use
>> a QName or CURIE (e.g., xsi:lala should dereference to
>> http://www.w3.org/2001/XMLSchema-instance#lala - basically it has to do
>> with how the resource at the end of the namespace URI is constructed,
>> and how its components are accessed.  If the resource masquerades as a
>> folder, then http://www.w3.org/2001/XMLSchema-instance/lala will
>> magically return the description for lala.  If it masquerades as a
>> document, then http://www.w3.org/2001/XMLSchema-instance#lala will
>> return the complete resource and there will be a ID within that resource
>> that corresponds to lala.
> Thanks, but doesn't this explanation just cover the "hash vs. slash" issue?
> What I was actually wondering about was the case when a namespace URI neither
> ends with hash nor slash.  Suppose
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance", what would xsi:lala
> expand to?  Nothing reasonable, I suppose, so why do such namespace URIs
> exist?
> Cheers,
> Christoph

Shane P. McCarron                          Phone: +1 763 786-8160 x120
Managing Director                            Fax: +1 763 786-8180
ApTest Minnesota                            Inet: shane@aptest.com
Received on Saturday, 24 January 2009 22:53:00 UTC

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