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   Re: [xml-dev] xs:group/xs:choice[@minOccurs | @maxOccurs]

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Bob Foster <bob@objfac.com> writes:

> I'm a bit puzzled by this. I can see why he can't have a
> minOccurs/maxOccurs on the group item as specified but why not on the
> choice nested in the group. This looks legal to me and I am curious
> what processors do not accept it.

On balance the reasoning the XML Schema WG went with was roughly this:

 1) Named model groups will be most useful if different references to
    them can have different min/max values;
 2) Allowing min/max on both references _and_ on the top level group
    in the named group definition, e.g.

       . . .
       <xs:group ref="myGroup" minOccurs="1" maxOccurs="10"/>
       . . .

    <xs:group name="myGroup">
     <xs:choice minOccurs="2" maxOccurs="4">
       . . .

    would be _very_ confusing and difficult to explain;
 3) So we rule out min/max on the top group in a named model group defn.

Note also that

     <xs:choice minOccurs="0" maxOccurs="unbounded">
       <xs:element name="e1"/>
       <xs:element name="e2"/>
       <xs:element name="e3"/>
means something _quite_ different from

       <xs:element name="e1" minOccurs="0" maxOccurs="unbounded"/>
       <xs:element name="e2" minOccurs="0" maxOccurs="unbounded"/>
       <xs:element name="e3" minOccurs="0" maxOccurs="unbounded"/>

For example, the first allows e1 e2 e1

The second does not.

 Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
                     Half-time member of W3C Team
    2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
            Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
                   URL: http://www.ltg.ed.ac.uk/~ht/
[mail really from me _always_ has this .sig -- mail without it is forged spam]


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