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RE: Ambiguous content models -- allowed or disallowed by XSDL?

From: Dare Obasanjo <dareo@microsoft.com>
Date: Wed, 12 Jun 2002 09:21:04 -0700
Message-ID: <8BD7226E07DDFF49AF5EF4030ACE0B7E06621CCE@red-msg-06.redmond.corp.microsoft.com>
To: "Morris Matsa" <mmatsa@us.ibm.com>, "Ian Stokes-Rees" <ijs@decisionsoft.com>
Cc: <xmlschema-dev@w3.org>

I fail to see how you can state that the REC allows for ambiguous content models when the very link you provide to the normative part of the spec dissalows it and I quote: 
"A content model must be formed such that during ·validation· of an element information item sequence, the particle contained directly, indirectly or ·implicitly· therein with which to attempt to ·validate· each item in the sequence in turn can be uniquely determined WITHOUT EXAMINING THE CONTENT OR ATTRIBUTES OF THAT ITEM, AND WITHOUT ANY INFORMATION ABOUT THE ITEMS IN THE REMAINDER OF THE SEQUENCE" 
similarly the non-normative part of the recommendation clarifies this point: 
A content model will violate the unique attribution constraint if it contains two particles which ·overlap· and which either 
* are both in the {particles} of a choice or all group 
* may ·validate· adjacent information items and the first has {min occurs} less than {max occurs}. 

	-----Original Message----- 
	From: Morris Matsa [mailto:mmatsa@us.ibm.com] 
	Sent: Wed 6/12/2002 8:54 AM 
	To: Ian Stokes-Rees 
	Cc: xmlschema-dev@w3.org 
	Subject: Re: Ambiguous content models -- allowed or disallowed by XSDL?

	> I believe it does explicitly disallow ACMs,
	> and would appreciate some clarification from those who are better versed
	> on the subject.
	My understanding of the rec:  Ambiguous content models are allowed.  What
	is required is that by looking at the next tag's name I must already be
	able to unambiguously attribute it to a given unique particle in the
	schema.  This disallows most ambiguous content models but allows some of
	them.  The rec includes a constraint for this [1], and a non-normative
	explanation. [2]
	[1] http://www.w3.org/TR/xmlschema-1/#cos-nonambig
	[2] http://www.w3.org/TR/xmlschema-1/#non-ambig
Received on Wednesday, 12 June 2002 12:21:37 UTC

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