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[Bug 5507] Symbol spaces need clearer description

From: <bugzilla@wiggum.w3.org>
Date: Thu, 08 Oct 2009 23:06:38 +0000
To: www-xml-schema-comments@w3.org
Message-Id: <E1Mw24E-0003J8-P1@wiggum.w3.org>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=5507


Noah Mendelsohn <noah_mendelsohn@us.ibm.com> changed:

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                 CC|                            |noah_mendelsohn@us.ibm.com




--- Comment #4 from Noah Mendelsohn <noah_mendelsohn@us.ibm.com>  2009-10-08 23:06:38 ---
Rgarding the example:

 <complexType name="upa-demo">
    <sequence>
      <element name="a"/>
      <element name="a" minOccurs="0"/>
    </sequence>
  </complexType>

Doesn't this bug just remind us once again that our notion of component
identity is murky?  Specifically,
http://www.w3.org/TR/xmlschema11-1/#dcl.elt.local says:

"If the <element> element information item has <complexType> or <group> as an
ancestor, and the ref [attribute] is absent, and it does not have
minOccurs=maxOccurs=0, then it maps both to a Particle and to a local Element
Declaration which is the {term}  of that Particle. "

The obvious difference between the two name="a" lines is in the minOccurs,
which maps to the particle, not the element declaration.  That then begs the
question of whether the element declaration that is the term of the respective
particles is the "same" or not.  Turning the argument around, the statement
that 

"Every complex type definition defines its own local attribute and element
declaration symbol spaces."

can be taken is at least indirect evidence that the answer is: they are the
same.  In any case, this suggests another possible resolution, in addition to
the one suggested by MSM.  We could attempt to make clear that, at least in
cases like this, all local element declaration markup in the transfer syntax
that shares a compexType ancestor and that declares elements of the same
expanded name does indeed map to a single element declaration.  I think this
would be my preferred casuistry.

Noah


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Received on Thursday, 8 October 2009 23:06:42 GMT

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