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Re: [Fwd: Re: [XPath] Consistency Constraints]

From: Martin Duerst <duerst@w3.org>
Date: Mon, 16 Aug 2004 10:41:58 +0900
Message-Id: <4.2.0.58.J.20040816103112.0564bd30@localhost>
To: Jonathan Robie <jonathan.robie@datadirect.com>
Cc: Paul Cotton <pcotton@microsoft.com>, public-qt-comments@w3.org

Hello Jonathan,

See below

At 11:30 04/08/14 -0400, Jonathan Robie wrote:

>Date: Sat, 14 Aug 2004 08:42:18 -0400
>From: Jonathan Robie <jonathan.robie@datadirect.com>
>To: public-qt-comments@w3.org
>Subject: Re: [XPath] Consistency Constraints
>X-Archived-At: http://www.w3.org/mid/411E08AA.3040901@datadirect.com

>Hi Martin,
>
>I'm classifying remaining issues for XPath 2.0, and I ran across the 
>following message from you:
>
>http://lists.w3.org/Archives/Public/public-qt-comments/2004Feb/0386.html
>
>In this, you ask:
>
>>2.2.5 says: "Enforcement of these consistency Constraints is
>>beyond the scope of this specification."
>>Who/what enforces these constraints? In case they are not enforced,
>>what are they there for?
>
>To me, the answer is given in the following paragraph:
>
>>In order for XQuery to be well defined, the data model, the static
>>context, and the dynamic context must be mutually consistent. The
>>consistency constraints listed below are prerequisites for correct
>>functioning of an XQuery implementation. Enforcement of these
>>consistency constraints is beyond the scope of this specification.
>>This specification does not define the result of a query under any
>>condition in which one or more of these constraints is not satisfied.
>
>An implementation must ensure that these constraints are met, or else our 
>specification is not well-defined for that implementation. We don't try to 
>design the language for any implementation that does not enforce the 
>consistency constraints.

If an implementation must ensure that the constraints are met, then
I don't understand why the spec then goes on to say "Enforcement of
these consistency constraints is beyond the scope of this specification."
I think it should rather say something like "If the constraints are
not met, then an implementation has to stop immediately and produce
an appropriate error message.", or whatever the usual wording for
draconic errors is in the XQuery spec.

I couldn't immagine the XML spec reading something like:
"Well-formedness is a prerequisite for the correct functioning
of XML. Enforcement of well-formedness is beyond the scope of
the XML specification.", and if it's not appropriate for XML,
then I can't see this being appropriate for XML Query.

>Is that clear now? Can we close this issue, or is there an issue that I am 
>not aware of?

I may be misunderstanding what you want to say with the above text,
but in any case, I think the text needs to be fixed.


Regards,    Martin.
Received on Monday, 16 August 2004 01:51:04 UTC

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