RE: Either-Or elements

<xsd:complexType name="somethingType"> 
        <xsd:choice> 
                <xsd:element name="foo" /> 
                <xsd:element name="bar" /> 
        </xsd:choice> 
</xsd:complexType> 

 
________________________________

From: xmlschema-dev-request@w3.org on behalf of RPearse@360commerce.com
Sent: Mon 3/21/2005 11:02 AM
To: xmlschema-dev@w3.org
Subject: Either-Or elements



Using a DTD, I can specify that the something element can only have foo or bar, but not both with this: <!ELEMENT something ((foo|bar)*)> 

In an XSD, I would have this: 

<?xml version="1.0"?> 

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> 

<xsd:element name="something" type="somethingType" /> 

<xsd:complexType name="somethingType"> 
        <xsd:sequence> 
                <xsd:element name="foo" minOccurs="1" maxOccurs="1" /> 
                <xsd:element name="bar" minOccurs="1" maxOccurs="1" /> 
        </xsd:sequence> 
</xsd:complexType> 

How would I specify that the user has to have the foo or bar element, but not both? Currently, this XSD seems to require that you have exactly one foo and one bar in your instance document. 

Thanks, 

Robert