Re: [Bug 11716] Identity constraints: grammatical typo

I think this is a classic case where the grammatical error and the minor 
confusion over sets-vs-sequences betray a much deeper and more serious 
problem (they make the text difficult to read, which means that the 
reader/reviewer tends to miss the technical problems).

There are two main technical problems here. Firstly, there's some kind 
of rule along the lines that each field must select zero or one relevant 
nodes, and because of the confusion surrounding skipped nodes and nodes 
with complex-type-with-complex-content, it's quite unclear what the 
actual rule really is. 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.

Michael Kay
Saxonica

On 11/01/2011 18:29, Henry S. Thompson wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> MSM writes:
>
>> In re comment 2:  speaking for myself, the replacement of the term "node set"
>> with the term "node sequence" does not seem to me to be unmotivated; the term
>> "node set" in XPath 1.0 is a bit of a misnomer, since the nodes are sequenced,
>> and the term "node set" is no longer used in the version of XPath to which XSD
>> normatively refers.  My personal view is that many more occurrences of 'set'
>> ought to have been replaced here by current terminology, but the WG decided
>> otherwise.
> It was the removal of "exactly", not the change from 'sequence' to
> 'set' that I was commenting on.
>
>> I also cannot find the phrase "a node sequence one of whose members" in the
>> status-quo text of clause 3 of the constraint; are we looking at the same
>> version of the document?  Or is Henry suggesting, in comment 2, that the scope
>> of the issue be broadened from clause 3 to clause 4, or to some larger area of
>> the text?
> 3 and 4, yes.
>
>> The change to clause 4 was made to resolve bug 5781 and was approved 17 April
>> 2009; see discussion in bug 5781 and in the April 2009 archive.
> Thanks, that's helpful.  Certainly my _intent_ in offering new wording
> was not to change 'set' vs. 'sequence' anywhere -- if I have done so
> inadvertently please correct it.
>
>> The subject/verb agreement problem and the ambiguous reference to "those
>> node-sets" in clause 3 were introduced in XSD 1.0 and were apparently not
>> caught (or were thought clear) when this constraint was revised.
> Indeed, not a new problem.  Still might be worth fixing, IMO.
>
> 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]
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.2.6 (GNU/Linux)
>
> iD8DBQFNLKGFkjnJixAXWBoRAo78AJ9jjN7OiZzontsiIHQZEjnve8E16wCeNt8S
> UR3gOGH8LYu7hLZXy4fSDSA=
> =yazF
> -----END PGP SIGNATURE-----
>
>

Received on Wednesday, 12 January 2011 00:00:18 UTC