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Re: Element content

You might also consider making the middle name element optional. For

   <!ELEMENT Person (FirstName, MiddleName?, LastName)>

Depending on your personal philosophy, a zero-length strengh might be
different from a missing element.

-- Ron

Wayne Steele wrote:
> A DTD cannot express this constraint.
> Anywhere CDATA can occur, an empty string is equally welcome.
> If you have a lot of constraints that you cannot express using DTDs, you
> might want to look at Schematron:
>    http://www.ascc.net/xml/resource/schematron/schematron.html
> >From: Mick McRae <Mick.McRae@abci.gov.au>
> >I have a basic XML document which references a DTD.  The document may have
> >some tags as follows;
> >
> ><?xml version="1.0" encoding="UTF-8"?>
> ><!DOCTYPE StaffReport SYSTEM "file:/opt/app/java/staff.dtd">
> ><StaffReport>
> >   <Person>
> >     <Firstname>Mick</Firstname>
> >     <MiddleName></MiddleName>
> >     <Surname></Surname>
> >   <Person>
> ></StaffReport>
> >
> >
> >Is it possible within the DTD to specify that certain elements cannot be
> >empty?  For example, in the sample XML above, I would like
> ><MiddleName></MiddleName> to be valid, as a middle name is not required,
> >but <Surname></Surname> not valid, as a surname is required.  Can I do this
> >or do I need to explicity test for the tag name and length when pasring the
> >document using SAX?
> >
> >Any help appreciated?