Steve Fletcher <ste.fletch@g...> wrote in
<4398c444-76a8-4ea3-a3ba-1f43a55cb323@s...>:
> I'm writing a schema, and I want to apply some contraints
> to the combination of values that can be supplied for the
> attributes for one of the elements. The problem concerns
> the Operation element in the xml fragment below. The
> element has two attrbiutes, and I want to apply some rules
> that ensure that the values provided are in agreement with
> one another. For example, I want ensure the CREATE, UPDATE
> and DELETE values for the Operation attribute are provided
> with a Sequence number, but that the CREATEUPDATE value of
> Operation attribute is not have a Sequence Number
> provided.
> 
> I want to <b>allow</b> only the following combinations:

Note that HTML markup is inappropriate in a Content-Type:
text/plain; charset=ISO-8859-1 document.

> <ns1:Operation Operation='CREATE' Sequence=(any +ve int)/>
> <ns1:Data>Data</ns1:Data>
> ...
> <ns1:Operation Operation="UDPATE' Sequence=(any +ve int)/>
> <ns1:Data>Data</ns1:Data>
> ...
> <ns1:Operation Oprtation='DELETE' Sequence=(any +ve int)/>
> <ns1:Data>Data</ns1:Data>
> ...
> <ns1:Operation Operation='CREATEUPDATE'/>
> <ns1:Data>Data</ns1:Data>
> 
> but <b>prevent<b/> the following xml
> <ns1:Operation Operation='CREATEUPDATE' Sequence=(any +ve
> int)/> <ns1:Data>Data</ns1:Data>
> 
> Does anyone know how this is achieved?

There's a number of traditional ways of dealing with
requirements like this.

  1). Use <create>, <update>, <delete> and <createupdate>
      elements instead of a generic <Operation> element.
  2). Check on the application side.
  3). Use a more powerful schema definition language, such
      as RELAX NG or Schematron constraint checking
      language.

By the way, just wondering, - are your <Data> elements
supposed to provide additional information about the
preceding <Operation> element?

-- 
<>There is no phenotype</>