Frank --

> I don't think that xml is off topic at all.

Most reassuring.

> but it doesn't go all the way and I guess something like LaTeX still
> has a place in the game;

An XML document type is just a model of a language.  I believe that
old designs were optimized for processor writers at the expense of
authors.  I have been trying to optimize document type design for the
traditional LaTeX author.

LaTeX itself is the primary back end to paper that I have in mind and
the only one I've written.

                                     -- Bill