Dan,

You can't do it in W3C XML Schema language. You can do it in some of 
the other schema languages.

However, your examples sound like you have some control over the XML. 
You can do something like the following:

<foo>
   <modeone/>
   <data1>aaa</data1>
   <data2>bbb</data2>
</foo>

<foo>
   <modetwo/>
   <data3>ccc</data3>
   <data4>ddd</data4>
</foo>

Regards,
Don Bate

At 11:32 AM -0400 7/7/04, Dan White wrote:
>I need a pointer or two about creating a schema.
>
>I have a situation where the incoming XML will have an element/attribute
>specifying one of four enumerated choices.  Depending on the value of that
>choice, the elements that follow will be different.
>
>Like this:
><foo>
>   <mode>one</mode>
>   <data1>aaa</data1>
>   <data2>bbb</data2>
></foo
>
><foo>
>   <mode>two</mode>
>   <data3>ccc</data3>
>   <data4>ddd</data4>
></foo>
>
>or
><foo mode="one">
>   <data1>aaa</data1>
>   <data2>bbb</data2>
></foo
>
><foo mode="two">
>   <data3>ccc</data3>
>   <data4>ddd</data4>
></foo>
>
>How does one set up the schema to validate the appropriate sequence of
>elements based on the value of the "controlling" element/attribute ?
>
>Thanks in advance.
>
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-- 
Don Bate               | Specializing in Consulting and Mentoring in
Bate Consulting, Inc   | Object-Oriented Technologies,
                        | Software Architecture, and Software Process
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