W3C home > Mailing lists > Public > www-tag@w3.org > March 2002

RE: "canonical" URIs

From: Biron,Paul V <Paul.V.Biron@kp.org>
Date: Tue, 19 Mar 2002 14:14:56 -0800
Message-Id: <8904C60CACA7D51191BC00805FEAAF4358EB72@crdc-exch-7.crdc.kp.org>
To: "'David Orchard'" <david.orchard@bea.com>, www-tag@w3.org
> -----Original Message-----
> From:	David Orchard [SMTP:david.orchard@bea.com]
> Sent:	Tuesday, March 19, 2002 10:05 AM
> To:	www-tag@w3.org
> Subject:	RE: "canonical" URIs
> TAG members,
> I don't see URI comparison officially listed as a TAG issue.  I'd like
> Joseph/Stephen's issue added to the TAG issues list.
> Equivalence rules for URIs are defined by the URI scheme.  HTTP has a
> section on URI comparison.
> However, XML does not have a default comparison function for the XML
> Schema
> anyURI data type.  I think a reasonable approach would be to say that the
> default comparision function for anyURI is to use the HTTP URI comparison
> algorithm, but that it is overridable by any scheme.
Our intention (given enough time I'm sure I could find the minutes
documenting this) was that equivalence for xs:anyURI was exactly as stated
in the namespaces rec (i.e., "character-by-character", simple binary string
compare) but you are right, that is not spelled out (I submitted this issue
for a potential erratum).  Why?  Because it thought it was to be too much of
a burden on processors to check things on a scheme-specific basis...plus,
what is a processor to do with a scheme that it has never heard of?

For what its worth, from a purely schema validation perspective, a
comparison/equivalence function on anyURI is only necessary for testing
whether a literal is included in a type derived from anyURI with one or more
values given for the enumeration facet.

Received on Tuesday, 19 March 2002 17:31:16 UTC

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