Tag list/DTD

Hello,

First of all, I'm a newbie.
I'd like to run a web page through a self-made parser and identify all
tags in the page that don't conform to HTML or XHTML.  Is there a simple
list of all HTML and/or XHTML tags that I can use for comparison (aside
from the DTD...maybe just a line-for-line list of tags?)  Of course, if
there's an easy way to utilize the DTD to do this, that would be best.

I could run the page through HTML Tidy or JTidy, capturing unknown tags,
but then I'd have to run the program each time I came across an unknown
tag (after updating the parser to accept the new tag).

Any thoughts?
Thanks,

Ryan