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Re: Unique Particle Attribution question

From: <noah_mendelsohn@us.ibm.com>
Date: Thu, 28 Mar 2002 12:17:16 -0500
To: "Kriegesmann, Peter" <Peter.Kriegesmann@softwareag.com>
Cc: xmlschema-dev@w3.org
Message-ID: <OFAF39ACBA.20930E57-ON85256B8A.005B122B@lotus.com>
In this version of the schema language, there is considered to be only one 
particle on the grammar you give, and hence no violoation of UPA.  This 
choice has some utility.  Also note that  an annotation on the particle 
can be reliably associated with the corresponding content (in this 
example, with both child elements.)

The Schema WG recognizes the sense in which there is in fact no unique 
attribution.  It does indeed complicate the construction of certain types 
of validator.  It's my impression that the WG may consider revising the 
UPA rule in future versions of schema (though there is debate is to 
whether or how to loosen or to tighten it.)

Noah Mendelsohn                              Voice: 1-617-693-4036
IBM Corporation                                Fax: 1-617-693-8676
One Rogers Street
Cambridge, MA 02142

"Kriegesmann, Peter" <Peter.Kriegesmann@softwareag.com>
Sent by: xmlschema-dev-request@w3.org
03/28/02 10:02 AM

        To:     xmlschema-dev@w3.org
        cc:     (bcc: Noah Mendelsohn/Cambridge/IBM)
        Subject:        Unique Particle Attribution question

Dear friends of the XML Schema,

Today I have another question about unique particle attribution as a 
of a discussion within our group.

Take a look at the following schema:

<?xml version = "1.0" encoding = "UTF-8"?>
<xs:schema xmlns:xs = "http://www.w3.org/2001/XMLSchema">
  <xs:element name = "rabbit">
      <xs:sequence minOccurs = "0" maxOccurs = "unbounded">
        <xs:element name = "egg" type = "xs:string"></xs:element>

and the corresponding xml document:


My question:

Does the schema violate against the "Unique particle attribution" [1] ?. 

My colleague says yes, because it cannot be determined, if the 2
"egg"-elements are a product of 1 or 2 sequence-elements and so the part 
the unique particle attribution [1]("each item in the sequence in turn can
be uniquely determined") is not fulfilled.
In my opinion and according to [2] (which does not claim to be complete) I
do not see a violation, because there is no "overlap" and each item can be
uniquely determined, as there is only one matching element definition
(element-definition of "egg").

The XML document also passes IBM Schema Quality Checker without warnings 

Your help and opinion is welcome.

Best regards,


[1] http://www.w3.org/TR/xmlschema-1/#coss-modelGroup
[2] http://www.w3.org/TR/xmlschema-1/#non-ambig

Peter Kriegesmann
Phone             06151-921484
Electronic Business Technologies (QE)            Fax
Software AG
Uhlandstrasse 12  
D-64297 Darmstadt
Received on Thursday, 28 March 2002 12:40:03 UTC

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