Making sure an element has a value

[madlarry]

Hi,

I am creating a DTD. I want to make sure that a value is entered into an element and not left blank.

For example, I have the following element:

<!ELEMENT firstname (#PCDATA)>

This allows someone to create an XML document without an actual value ( <firstname/> ).

How do I make sure that it always has a value?? (i.e. <firstname>fred</firstname> ).

I get the feeling I'm missing something pretty obvious!

Thanks,

madlarry