XSD schema and CALS table


Is it possible to have an XSD schema validate an XML document and check whether attributes of some elements are in a list of attributes defined in another set of elements in the same XML file.

For example:

Defined list

<tgroup cols="6">
      <colspec colnum="1" colname="col1"/>
      <colspec colnum="2" colname="col2"/>
      <colspec colnum="3" colname="col3"/>
      <colspec colnum="4" colname="col4"/>
      <colspec colnum="5" colname="col5"/>
      <colspec colnum="6" colname="col6"/>

.....the rest of the file...

Part of a table
      <entry colname="col3">4 &amp; 7</entry>
      <entry colname="col4"/>
      <entry colname="col5">1500-1600 &#8486; approx.</entry>

I want the schema to only allow entry elements to have colname attributes with values defined in the colname attributes of the colspec elements.

The number of colspec elements varies form one XML file to another so it is not really possible to use enumeration values based on restriction type NMTOKEN

Can anyone help please?


Who is Participating?
rdcproConnect With a Mentor Commented:
This is called a co-occurance constraint, and it's not possible in W3C XML Schema.  You can do this with Schematron or RelaxNG, which uses XSLT internally to provide this functionality.  Most of the time, when we want to use W3C XML Schema with this type of constraint, we enforce this externally with some sort of business rule validation.  So you validate the document with the Schema to check the types, then check the co-occurance constraints using a second step.  

Mike Sharp
BTW, I meant Schematron uses an internal XSLT for this...Frankly I don't know how RelaxNG does it, but I wouldn't be surprised if it did it the same way.  

Mike Sharp
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