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Re: Component representation of xs:group ref="x"

From: <noah_mendelsohn@us.ibm.com>
Date: Thu, 4 Nov 2004 15:30:24 -0500
To: "Michael Kay" <mike@saxonica.com>
Cc: xmlschema-dev@w3.org
Message-ID: <OF03744301.5C6C0815-ON85256F42.006AB958@lotus.com>

Michael Kay writes:

>> In fact, the model group definition itself 
>> seems to be completely redundant as a schema 
>> component, because there is nothing that
>> refers to it.

I'll leave it to Henry or others to deal with other aspects of your query, 
but on a few points I think I can help. 

I believe that the MGD is an unusual component in that, as you note, it is 
not typically referenced by other components.  That does not mean it's 
completely redundant however.  It exists as a potential referent of a 
<group ref=" "/>.  So, you would be correct in saying that MGD is 
redundant in situations in which you can be sure that either no schema 
documents are to be employed, or in which all such schema documents have 
already been converted to components per the mapping rules. 

>> Neither 3.9.2, which discusses particles, 
>> nor 3.8.2, which discusses model groups, 
>> seems to explain how the <xs:group ref=""> 
>> representation is translated into schema 
>> components. In fact, 3.9.2 seems to point 
>> you to 3.8.2, and 3.8.2 doesn't acknowledge 
>> the existence of named groups at all.

Right, but I believe that 3.7.2 which discusses named model groups does 
[1]:

Note that in the mapping of <group ref="..."/>, the {term} in 3.7.2 is:

        {term}  The {model group} of the model 
                  group definition ·resolved· to 
                  by the ·actual value· of the 
                  ref [attribute]


So the MGD is not redundant in any situation where you will appeal to the 
above mapping. 

Noah

[1] 
http://www.w3.org/TR/2004/PER-xmlschema-1-20040318/#declare-namedModelGroup


--------------------------------------
Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
1-617-693-4036
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Received on Thursday, 4 November 2004 20:31:17 UTC

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