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RE: XQuery 1.0 and XPath 2.0 Functions and Operators: http://www.w3.org/2005/xpath-functions/collation/codepoint

From: Michael Kay <mike@saxonica.com>
Date: Tue, 15 Sep 2009 15:10:43 +0100
To: "'Patrick Durusau'" <patrick@durusau.net>, <public-qt-comments@w3.org>
Message-ID: <DBCC3CED6F8E4B318B157186DB5E071F@Sealion>
> Is "Unicode code point collation *defined* in the 
> XPath/XQuery/XSLT/etc. 
> family of standards or it is simply *named*?
> (If it is defined, a hint as to where to find that definition would be
> appreciated.)

I believe you are correct: the specifications contain no formal definition
of this collation.
> I would suspect that defining it would involve at a minimum 
> specifying some default Unicode normalization as well as what 
> happens after normalization.

It is not intended that this collation should perform any normalization. The
definition is essentially as follows: let X be the sequence of integer
codepoints representing the string x, and let Y be the sequence of integer
codepoints representing the string y. Then the integers of these two
sequences are compared pairwise until a pair is found that differ or until
one or both sequences are exhausted. If a pair is found that differ, then
the lesser of the strings is the one that contains the lesser integer in
this position; if both sequences are exhausted then the strings are equal;
if only one sequence is exhausted then the lesser string is the one whose
codepoint sequence is exhausted.
> PS: If this is the wrong list, please suggest the correct 
> one. This seemed to me to be more of a question about the 
> standard per se than about XQuery or XPath, although the 
> answer would have an impact on both.

I have raised the problem on your behalf at


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Michael Kay
(personal response)
Received on Tuesday, 15 September 2009 14:11:23 UTC

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