You don't need the named group, you could do the following which is
equivalent:
 
    <xs:complexType name="conditions" > 
        <xs:sequence>  
            <xs:choice minOccurs="0" maxOccurs="unbounded"> 
               <xs:element name="primitive_condition_0" /> 
               <xs:element name="primitive_condition_1" /> 
               <xs:element name="primitive_condition_2" /> 
            </xs:choice> 

            <xs:element name="complex_condition" =
type="complex_condition"
minOccurs="0" maxOccurs="unbounded" /> 
        </xs:sequence> 
    </xs:complexType> 
    
Michael Kay
http://www.saxonica.com/


  _____  

From: xmlschema-dev-request@w... [mailto:xmlschema-dev-request@w...] =
On
Behalf Of Kl=F6ck, Erwin
Sent: 13 February 2009 15:41
To: xmlschema-dev@w...
Subject: Best way to ensure one element out of a set




Hi, 

is this the best way to ensure that one element out of a set is used? 
I have the following xml: 

--- test.xml begin --- 
<?xml version="1.0" encoding="ISO-8859-1"?> 
<top xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
     xsi:noNamespaceSchemaLocation="test.xsd"> 
     
     <conditions> 

         <primitive_condition_0 /> 
         <primitive_condition_1 /> 
         <primitive_condition_2 />    

         <complex_condition /> 
     </conditions> 
</top> 
--- test.xml end --- 

I want to make sure that at least one of the primitive_condition =
elements
ist used, but I don't care which one. 
I have come up with the following solution (which works) but are now
wondering if this is the best way to do this. 
My qestion is: Is there a more straight forward way to do this than to =
have
a group of choices? 

--- test.xsd begin --- 
<?xml version="1.0" encoding="UTF-8"?> 
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> 
    <xs:element name="top" > 
        <xs:complexType> 
            <xs:sequence> 
                <xs:element name="conditions" type="conditions" /> 
            </xs:sequence> 
        </xs:complexType> 
    </xs:element> 
    
    <xs:complexType name="conditions" > 
        <xs:sequence> 
            <xs:group ref="primitive_conditon" minOccurs="0"
maxOccurs="unbounded" /> 
            <xs:element name="complex_condition" =
type="complex_condition"
minOccurs="0" maxOccurs="unbounded" /> 
        </xs:sequence> 
    </xs:complexType> 
    
    <xs:group name="primitive_conditon" > 
        <xs:choice> 
            <xs:element name="primitive_condition_0" /> 
            <xs:element name="primitive_condition_1" /> 
            <xs:element name="primitive_condition_2" /> 
        </xs:choice> 
    </xs:group> 
    
    <xs:complexType name="complex_condition" /> 
</xs:schema> 
--- test.xsd end --- 

Thanks for taking an interest. 

Erwin