RE: UPA or not UPA violation?

Remember what UPA stands for: unique particle attribution. Every child
element can be unambiguously associated with exactly one particle in the
content model. If there are no child elements, this is trivially true.

Michael Kay
http://www.saxonica.com/ 

> -----Original Message-----
> From: xmlschema-dev-request@w3.org 
> [mailto:xmlschema-dev-request@w3.org] On Behalf Of Florent Georges
> Sent: 16 April 2008 12:15
> To: xmlschema-dev@w3.org
> Subject: UPA or not UPA violation?
> 
> 
>   Hi
> 
>   Considering the following schema:
> 
>     <xs:group name="g1">
>        <xs:sequence>
>           <xs:element name="a" type="xs:int" minOccurs="0"/>
>           <xs:element name="b" type="xs:int" minOccurs="0"/>
>        </xs:sequence>
>     </xs:group>
> 
>     <xs:group name="g2">
>        <xs:sequence>
>           <xs:element name="c" type="xs:int" minOccurs="0"/>
>           <xs:element name="d" type="xs:int" minOccurs="0"/>
>        </xs:sequence>
>     </xs:group>
> 
>     <xs:element name="elem">
>        <xs:complexType>
>           <xs:sequence>
>              <xs:choice>
>                 <xs:group ref="g1"/>
>                 <xs:group ref="g2"/>
>              </xs:choice>
>           </xs:sequence>
>        </xs:complexType>
>     </xs:element>
> 
>   Should it be an UPA violation if we have an "elem" element 
> with no child?  Because in this case we know the content of 
> the element is either of the groups but we don't know which 
> one (because both can be empty).
> 
>   Or I missed something?
> 
>   Regards,
> 
> --drkm
> 
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