DTD for maxima internal form



> Stavros Macrakis wrote, in part:
> > What a DTD/Schema allows you to do is to specify restrictions on 
> > structures,

> I agree that checking against a grammar is a useful function. 
> If that's what we want, there's no need to drag in XML -- 

XML is useful as an interchange and archiving format.  For those
applications, the fact that it's standard across languages and systems
is as important as the actual functionality.

> I'm pretty sure that one could discover/invent equivalent 
> functionality, as applied to s-expressions, without much 
> trouble.

On the other hand, for internal use between two systems which already
understand S-expressions, there is no particular need for XML or for
DTDs.

So I'm not sure what need you are trying to address.

       -s