Re: Group redefinition and recursive content models.

Eddie Robertsson wrote:

> Eric van der Vlist wrote:
> 
> 
>>Just wondering how a recursive group such as:
>>
>>  <xs:group name="group">
>>   <xs:sequence>
>>     <xs:element name="foo">
>>      <xs:complexType>
>>        <xs:group ref="group" minOccurs="0"/>
>>      </xs:complexType>
>>     </xs:element>
>>     <xs:element name="bar" type="xs:token"/>
>>   </xs:sequence>
>>  </xs:group>
>>
>>may be redefine without confusion between the <xs:group ref="group"/>
>>meaning "extension", the <xs:group ref="group" minOccurs="0"/> meaning
>>"bogus extension" the <xs:group ref="group" minOccurs="0"/> meaning
>>"reference" ???
>>
> 
> Jeez Eric, with a sentence like that I think you just qualified to be writing
> specs yourself ;-)


:)


> 
> Anyway, isn't this already covered in the spec:
> 
> "6 Within the [children], for each <group> the appropriate case among the
> following must be true:
> 6.1 If it has a <group> among its contents at some level the ·actual value·
> of whose ref [attribute] is the same as the ·actual value· of its own name
> attribute plus target namespace, then all of the following must be true:
> 6.1.1 It must have exactly one such group.
> ..."
> 
> It seems that 6.1.1 prohibits a redefinition of your above example since it
> would have to groups among its contents at some level where the ref attribute
> is the same as its own name.


Yes, this is exactly what I meant by "confusion"! The fact to use a 
reference to extend a group is ambiguous and overlaps with the "normal" 
semantic of group references.

IMO, a clean derivation method should be provided for groups...

Thanks

Eric


>

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