W3C home > Mailing lists > Public > xml-uri@w3.org > May 2000

Where's the bone of contention? (small clarification)

From: Al Gilman <asgilman@iamdigex.net>
Date: Tue, 23 May 2000 14:54:56 -0500
Message-Id: <200005231845.OAA1063469@smtp1.mail.iamworld.net>
To: xml-uri@w3.org
At 09:16 AM 2000-05-23 -0400, Paul W. Abrahams wrote:
>James Clark wrote:
>
>> The problematic case is when you have
>> two URI references that are identical when compared as strings but refer
>> to different resources (because they have different base URIs).  This is
>> like having obj1 == obj2 but not obj1.equals(obj2).  I would call that
>> inconsistent.  By only comparing absolute URIs (either because you
>> forbib relative URIs or because you absolutize first), you guarantee
>> that if two namespace names compare equal then they refer to the same
>> resource.
>
>But can that case arise in the namespace spec itself?  Comparison occurs
in only
>one context: verifying the uniqueness of attributes.  And that comparison
>necessarily occurs within a single element, thus ensuring that both
elements being
>compared have the same context and therefore would absolutize identically.
>

This is a narrower reading of the Namespaces Rec than some people would
seem to apply.  The other comparison which may or may not be intended or
implied has to do with "binding the elements and attributes in the document
syntax-as-recognized to appropriate further processing."  This is where
some vagueness lies, and we are exploring how to articulate a layering in a
backward-nondestructive, and forward-constructive, fashion.

>If I've overlooked something, do you have an example showing how the
uniqueness
>test can give misleading results because of different absolutizations of the
>attributes being compared?

It's not the uniqueness test, it's the "suitability for [further]
processing" test.  This is exactly the distinction I was trying to raise
earlier between "distinguishing tokens" and "recognizing names."

The syntactic processing needs to be safe from fear of contradiction by
"higher layers."  But the syntactic processing should not, in technical
contexts, be baldly termed "XML processing," as if it were all there is to
XML processing.  This suffers too much risk of introducing confusion and
generating more flameage.  Please recognize that some will read the term
"XML processing" as referring to the open domain of what XML may become and
not just the closed domain of what it is already documented to be.

Al

>
>Paul Abrahams
> 
Received on Tuesday, 23 May 2000 14:43:24 UTC

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