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[Bug 6513] [XQuery] inconsistent terminology in definition of derives-from()

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Date: Tue, 17 Mar 2009 10:50:05 +0000
To: public-qt-comments@w3.org
Message-Id: <E1LjWs1-0005tT-IM@wiggum.w3.org>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=6513





--- Comment #12 from Michael Kay <mike@saxonica.com>  2009-03-17 10:50:05 ---
>To me, the open question is whether the assembled schema is imported, after all schema import, include, redefine, etc. has been done. 

I think it's best to avoid the verb "imported" unless it's very precisely
defined. The "import schema" declaration certainly causes the instantiation of
a schema (=set of schema components) that many contain components in many
namespaces, and the question is whether the ISSD of the module should contain
the names of all those components, or only those names that are in the
namespace that is the target of the import. The analogy with xs:import and with
"import module" suggests that it should only be the names in the target
namespace.

>But if the answer were "no", this would not be a statically known type in M1 as defined in the XQuery specification. It's not in the ISSD of the module. I don't think the specification is ambiguous on this.

The specification doesn't actually use the phrase "statically known type", let
alone define it. In 2.5.4 it uses "known type" as a synonym for "type present
in the ISSD", and the confusion/ambiguity in this bug report arises because of
the tacit acknowledgement in the text that the processor might also know about
types that are not in the ISSD.

Meanwhile, as highlighted in bug #5738, section 2.2.5 imposes a constraint that
if type T is in the ISSD, then all types derived by extension from T, if they
appear in a run-time instance, must also be in the ISSD. This is too strong;
the section should recognize, as 2.5.4 does, that the processor may know about
things even though they are not in the ISSD. (It is also too strong because a
processor that doesn't know about all types derived by extension can function
perfectly well provided it avoids making inferences on the assumption that it
does know about all such types.)


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Received on Tuesday, 17 March 2009 10:50:15 GMT

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