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[Bug 6011] [schema11] base URI comments

From: <bugzilla@wiggum.w3.org>
Date: Tue, 25 Nov 2008 01:15:23 +0000
To: www-xml-schema-comments@w3.org
Message-Id: <E1L4mWR-0001IN-1X@farnsworth.w3.org>

http://www.w3.org/Bugs/Public/show_bug.cgi?id=6011


C. M. Sperberg-McQueen <cmsmcq@w3.org> changed:

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--- Comment #6 from C. M. Sperberg-McQueen <cmsmcq@w3.org>  2008-11-25 01:15:22 ---
John,

Thank you for the comment on the opening paragraph of appendix E,
which for convenience I reproduce in full:

    This specification requires as a precondition for ·assessment· an
    information set as defined in [XML-Infoset].  The result of
    assessment may depend upon the following information items and
    properties. For interoperability, processors should accurately
    reflect these properties of the input to validity assessment.

The second and third sentences were inserted in a recent revision of
the text, in connection with the resolution of bug 5800 (for those who
need them, the minutes of the relevant meeting are at
http://lists.w3.org/Archives/Member/w3c-xml-schema-ig/2008Oct/0007.html).

The editors have not checked with the Working Group yet, but our
understanding of the sentence "For ... assessment" is that it means
NOT (as I think you take it)

    For interoperability, processors SHOULD expose the following
    information items and properties in their representation of the
    PSVI (and do so accurately) of the document.

but instead something more like

    For interoperability, processors SHOULD be careful to be 
    accurate in establishing the values of the following 
    information items and properties (since the result of 
    assessment depends on them).

The problem may lie in the verb "reflect", which was chosen to allow
the text to get rid of the verb "support" (which one WG member
described as "always a weasel word") but which turns out to suffer
from frailties of its own.

I think the WG should choose among the following courses of action:

1) Adopt the wording proposed by John Arwe in comment 5, which 
replaces "For ... assessment" with:

    For interoperability, processors should behave as if these
    properties were copied from the validity assessment episode's
    input infoset to the resulting infoset.  That is, the validity
    assessment episode's output infoset should expose these properties
    and their respective values should match the input infoset.

This would entail an understanding of the text which differs radically
from mine; in general, the XSD 1.1 spec works hard NOT to make any
recommendations about what PSVI information is exposed by a conforming
processor, and some WG members resisted even the proposal to provide
names for some defined subsets in Appendix D.1, on the grounds that
the names would be taken as recommendations.

2) Adopt the following alternative wording proposal, which replaces
the entire paragraph with:

    This specification requires as a precondition for ·assessment· an
    information set as defined in [XML-Infoset] which contains at
    least the following kinds of information items and properties.

This reverts to the wording of XSD 1.0, but replaces "supports" (which
is vague, and also ill matched with "information set" as its subject)
with "contains" (which is what an information set does to information
items and their properties, in the usage of the infoset spec).

3) Delete the sentence "For ... assessment" to make the paragraph
read:

    This specification requires as a precondition for ·assessment· an
    information set as defined in [XML-Infoset].  The result of
    assessment may depend upon the following information items and
    properties. 

>From the fact that assessment results depend on the information items
and properties mentioned, it seems clear already that interoperability
depends on validators taking some care to get the values of the
properties right.  It is hard to imagine a reader benefiting from the
explicit exhortation that validators SHOULD do so.

For what it's worth, my own recommendation is 2, or 3.


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Received on Tuesday, 25 November 2008 01:15:32 GMT

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