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[Bug 5469] substitution groups not that strictly limited

From: <bugzilla@wiggum.w3.org>
Date: Fri, 08 Feb 2008 23:04:48 +0000
To: www-xml-schema-comments@w3.org
Message-Id: <E1JNcH2-0002VY-BV@wiggum.w3.org>


           Summary: substitution groups not that strictly limited
           Product: XML Schema
           Version: 1.0 only
          Platform: Macintosh
               URL: http://www.w3.org/TR/2004/REC-xmlschema-1-
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P4
         Component: Structures: XSD Part 1
        AssignedTo: cmsmcq@w3.org
        ReportedBy: cmsmcq@w3.org
         QAContact: www-xml-schema-comments@w3.org
 BugsThisDependsOn: 5074

+++ This bug was initially created as a clone of Bug #5074, to allow
an issue reported for 1.1 to be tracked for 1.0 also +++

The substitution group definition (below) says member names can vary widely but
that member types are "strictly limited". This may be technically true, but
seems to suggest a false sense of security in use of substitution groups. By
default, with no derivation constraints, a substitution group can transitive
include wildly different types. That is, a restriction step can remove all
optional content and an extension step could introduce completely different

If my analysis is correct, please consider a milder statement and/or a warning
about unintentional extensibility.

--------------------- Element Substitution Group
All such members must have type definitions which are either the same as the
head's type definition or restrictions or extensions of it. Therefore, although
the names of elements can vary widely as new namespaces and members of the
Ěsubstitution groupĚ are defined, the content of member elements is strictly
limited according to the type definition of the Ěsubstitution groupĚ head.
Received on Friday, 8 February 2008 23:04:55 UTC

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