That's called a co-occurrance constraint, and W3C XML Schema doesn't support 
that.  You might be able to create a hack using substitution groups or 
something, but it would be ugly.

RelaxNG and Schematron both support co-occurance constraints, but these 
aren't W3C XML Schema--they're a separate syntax.  Schematron uses an XSLT 
to process this, so you could create your own validation rules for this.  As 
Han suggests, using xs:choice is the only way in schema to do this.

Regards,
Mike Sharp


"David W. Rogers" <DavidWRogers@d...> wrote in message 
news:9F5240CE-C4A1-4A6B-B5DF-5146D63FF6E2@m......
> Yes, I have considered xs:choice, however, I don't see how I would apply
> that. In this case, I always want all of the elements in the order listed,
> but, I only want to allow content (specific content) in one of those 
> elements.
>
> Thanks,
> David
>
> "Han" wrote:
>
>> Have you considered xs:choice instead of xs:sequence?
>> -- 
>> Pohwan Han. Seoul. Have a nice day.
>> "David W. Rogers" <DavidWRogers@d...> wrote in 
>> message
>> news:423DF2B1-74BC-4F26-AFE2-99592532806A@m......
>> >I am creating an evaluation form, to capture a question of the format:
>> >
>> > 1) I was able to hear everything the speaker said:
>> >
>> > Strongly Disagree       Neutral            Strongly Agree
>> >          [   ]                  [   ]                  [   ]
>> >   [   ]                  [   ]
>> >
>> > I am creating a schema to validate an XML document that has:
>> >
>> > <RankedQuery ID="1" Text="I was able to hear everything the speaker
>> > said:">
>> > <StronglyDisagree></StronglyDisagree>
>> > <SortofDisagree></SortofDisagree>
>> > <Neutral>x</Neutral>
>> > <SortofAgree></SortofAgree>
>> > <StronglyAgree></StronglyAgree>
>> > </RankedQuery>
>> >
>> >
>> > I only want one of these to be able to have an 'x' in it at a time 
>> > (like a
>> > radio button choice). My schema does not enforce that:
>> >
>> > <xs:element name="RankedQuery">
>> > <xs:complexType>
>> >  <xs:sequence>
>> >    <xs:element ref="StronglyDisagree"/>
>> >    <xs:element ref="SortofDisagree"/>
>> >    <xs:element ref="Neutral"/>
>> >    <xs:element ref="SortofAgree"/>
>> >    <xs:element ref="StronglyAgree"/>
>> >   </xs:sequence>
>> >  <xs:attribute name="ID" use="required" type="xs:integer"/>
>> >  <xs:attribute name="Text" use="required"/>
>> > </xs:complexType>
>> > </xs:element>
>> >
>> > <xs:element name="Neutral" type="xType"/>
>> > <xs:element name="SortofAgree" type="xType"/>
>> > <xs:element name="SortofDisagree" type="xType"/>
>> > <xs:element name="StronglyAgree" type="xType"/>
>> > <xs:element name="StronglyDisagree" type="xType"/>
>> > <xs:simpleType name="xType">
>> > <xs:restriction base="xs:string">
>> >  <xs:enumeration value=""/>
>> >  <xs:enumeration value="x"/>
>> >  <xs:enumeration value="X"/>
>> > </xs:restriction>
>> > </xs:simpleType>
>> >
>> >
>> > Can someone redirect me in a direction that will enforce that one and 
>> > only
>> > one of the xtype elements can have an 'x' in it?
>> >
>> > Thanks,
>> > David
>>
>>