Re: xs:choice question

I think you can change this to the following and get what you want:

 <xs:choice>
 <xs:sequence>
   <xs:element name="a" type="xs:string"/>
   <xs:element name="b" type="xs:string" minOccurs="0"/>
 </xs:sequence>
 <xs:element name="b" type="xs:string"/>
 </xs:choice>

The strategy works for simple cases like this, but doesn't extend well to 
having more elements that have to share the same sort of occurrence 
constraints.  This is an area that future schema recommendations are looking 
at.

HTH,

Pete.
--
=============================================
Pete Cordell
Codalogic Ltd
for XML Schema to C++ data binding visit
 http://www.codalogic.com/lmx/
=============================================

----- Original Message ----- 
From: "Markus Gamperl" <markus.gamperl@gmx.at>
To: <xmlschema-dev@w3.org>
Sent: Wednesday, June 27, 2007 8:21 PM
Subject: xs:choice question


>
> Hello!
>
> I have the following xml fragment example:
>
> <data>
> <a>a test</a>
> <b>b test</a>
> <data>
>
> the schema should check the following rules (three options):
> - element a must exist, b may not
> - element b must exist, a may not
> - element a and b must exist
>
> Therefor I have defined the following choice:
> ...
> <xs:choice>
> <xs:element name="a" type="xs:string"/>
> <xs:element name="b" type="xs:string"/>
> <xs:sequence>
>   <xs:element name="a" type="xs:string"/>
>   <xs:element name="b" type="xs:string"/>
> </xs:sequence>
> </xs:choice>
> ...
>
> The xml editor raises an error - something about non determenistic 
> declaration...
>
> Do you have a suggestion how to define these three rules?
>
> Thanks for your help!
> Markus
> -- 
> Psssst! Schon vom neuen GMX MultiMessenger gehört?
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>
>