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RE: complexContent w/ choice minOccurs=0

From: Mark Feblowitz <mfeblowitz@frictionless.com>
Date: Fri, 17 May 2002 12:33:25 -0400
Message-ID: <4DBDB4044ABED31183C000508BA0E97F040ABB7A@fcpostal.frictionless.com>
To: "'Jeni Tennison'" <jeni@jenitennison.com>, Tom Moog <tmoog@sarvega.com>
Cc: xmlschema-dev@w3.org
Would the same be the case for sequences? 

Is that something that is/will be enforced? 

If so, the implication would be that any choice or sequence that contained
completely optional content would also have to be marked optional
(minOccurs="0"). That would have a pretty profound impact on our schemas.


Mark Feblowitz                                   	
XML Architect
       [t]   617.715.7231                                     	
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Frictionless Commerce Incorporated 	
       [e]  mfeblowitz@frictionless.com
       [w] http://www.frictionless.com
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             Cambridge, MA 02139 
Open Applications Group Incorporated
       [e]  mfeblowitz@openapplications.org
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 -----Original Message-----
From: 	Jeni Tennison [mailto:jeni@jenitennison.com] 
Sent:	Friday, May 17, 2002 4:30 AM
To:	Tom Moog
Cc:	xmlschema-dev@w3.org
Subject:	Re: complexContent w/ choice minOccurs=0

Hi Tom,

> Question 1: If a <choice> has no children then what does it mean to
> have a minOccurs > 0 ?

Hmm... I think that it would mean an unsatisfiable schema. A choice
entails that you have to choose an option. If there's nothing to
choose from, then the constraint is unsatisfiable. In Section 3.8.4,
it points out:

  "Nothing in the above should be understood as ruling out groups
   whose {particles} is empty: although no sequence can be ·valid· with
   respect to such a group whose {compositor} is choice..."

> Question 2 (terminology): What is the author trying to say when he
> writes "the actual value 0" instead of "the value 0".

The minOccurs attribute defaults to the value 0, so if the minOccurs
attribute is missing, then it's the same as specifying it with the
value 0. "The actual value 0" means that the value is 0 whether or not
it was actually specified within the schema document itself; I guess
"the value 0" could be read as meaning that the value is 0 and it was
actually specified in the schema document.



Jeni Tennison
Received on Friday, 17 May 2002 12:35:08 UTC

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