- From: Henry S. Thompson <ht@inf.ed.ac.uk>
- Date: Wed, 12 Jan 2011 17:30:14 +0000
- To: Michael Kay <mike@saxonica.com>
- Cc: www-xml-schema-comments@w3.org
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Michael Kay writes:
> HST writes:
>> MK writes:
>>> Secondly, I think it's almost certainly intended that the key
>>> sequence for each selected node should contain one value (or absent)
>>> for each field in the constraint, and the rules fail to ensure this,
>>> especially in the case where the field expression selects an empty
>>> node-sequence.
>> So I think we disagree here about a matter of substance, which
>> none-the-less, curiously, doesn't affect any visible aspect of
>> processor behaviour (I don't think).
> . . .
> <root>
> <vehicle local-reg="ABC123"/>
> <vehicle national-reg="ABC123"/>
> </root>
>
> My assumption has been that the two key sequences are (.absent.,
> "ABC123") and ("ABC123", .absent.) respectively, and these are not
> equal. However, when I responded to the user on this one, I overlooked
> the impact of clause 4, whose effect appears to be:
>
> * for xs:key, the instance is invalid because the target node set and
> qualified node-set are not equal
>
> * for xs:unique, the instance is valid because the qualified node-set
> is empty. And counter-intuitively, the following instance is also
> valid for the same reason:
Ah, so the impact is _not_ vacuous, as I thought -- OK, so yes, we
really do _have_ to fix this, and clause 4 is definitely in scope.
ht
- --
Henry S. Thompson, School of Informatics, University of Edinburgh
10 Crichton Street, Edinburgh EH8 9AB, SCOTLAND -- (44) 131 650-4440
Fax: (44) 131 651-1426, e-mail: ht@inf.ed.ac.uk
URL: http://www.ltg.ed.ac.uk/~ht/
[mail from me _always_ has a .sig like this -- mail without it is forged spam]
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Received on Wednesday, 12 January 2011 17:35:46 UTC