In order to avoid misinterpretations I would like to suggest a change to=
 the unique constraint definition as follows.
Add an additional clause into the 3.11.4 paragraph:
=0D

3.11.4 Identity-constraint Definition Validation Rules

...
 =0D
4.1.1 The  <http://www.w3.org/TR/xmlschema-1/#key-tns> =B7target node set=
=B7 is a subset of the   <http://www.w3.org/TR/xmlschema-1/#key-qns> =
=B7qualified node set=B7, that is, every member of the =
 <http://www.w3.org/TR/xmlschema-1/#key-tns> =B7target node set=B7 is also=
 a member of the  <http://www.w3.org/TR/xmlschema-1/#key-qns> =B7qualified=
 node set=B7 however not every member of  =
 <http://www.w3.org/TR/xmlschema-1/#key-qns> =B7taget node set=B7 is a=
 member of  <http://www.w3.org/TR/xmlschema-1/#key-qns> =B7qualified node=
 set=B7.
...
=0D
Thanks
Eugene.

-----Original Message-----
From: Sandy Gao [mailto:sandygao@c...]
Sent: Tuesday, November 15, 2005 11:03 PM
To: Tishkin, Eugene
Cc: xmlschema-dev@w...
Subject: Re: unique constraint interpretation.



Just re-read the relevant clause in the spec a few times and came to the=
 conclusion that Xerces indeed has a bug. That is, the quoted conclusion is=
 not correct, and the testcase attached to 18405 should be valid.=0D

Thanks,
Sandy Gao
XML Parser Development, IBM Canada
(1-905) 413-3255
sandygao@c...




"Tishkin, Eugene" <etishkin@m...>=0D
Sent by: xmlschema-dev-request@w...=0D


11/09/2005 09:31 AM=0D


To
<xmlschema-dev@w...>=0D

cc

Subject
unique constraint interpretation.

=0D




Hi,=0D
 =0D
The below is the comment from Xerces parser BUG 18405 report:=0D
==========================
========================0D
"3 For each node in the
=B7target node set=B7
all of the
{fields},
with that node as the context node, evaluate to either an empty node-set or=
 a=0D
node-set with exactly one member, which must have a simple type."

The target node set is the set of nodes on which the selector is matched. =
 Note=0D
that this condition must hold for *any* identity constraint; only in bullet=
 4=0D
of the tableau are the differences between key and unique described. =0D
Therefore, it seems clear that, if a selector matches, then either all of=
 the=0D
fields must match or none of them must match; even for xsd:unique, you=
 can't=0D
have some fields matching.=0D
==========================
==========================
========0D
 =0D
Especially I'm interested in the conclusion:=0D
 =0D
"Therefore, it seems clear that, if a selector matches, then either all of=
 the=0D
fields must match or none of them must match; even for xsd:unique, you=
 can't=0D
have some fields matching."=0D
 =0D
Is this a correct interpretation of unique constraint?=0D
 =0D
Regards,=0D
Eugene=0D
 =0D


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