Nice answer...
>
>On a related note, there are lots of people on the Web with questions like
>this that do not konw how to read a DTD. Is there an introductionry
>text online?
Start here:
http://www.w3.org/hypertext/WWW/MarkUp/SGML/
All the interesting SGML online materials I've seen are there.
Of all those links, the one I'd recommend is:
Gentle Introduction to SGML
ftp://www.ucc.ie/pub/sgml/p2sg.ps
Dan