Following a suggestion from Lucas I've gone through the Poly/ML source code and produced an overview that describes where each file fits into the overall structure. It still needs work both on the text and on the layout but at least it's a start. It's in the documentation directory in SVN as documentation/Overview.html and on the web site as http://www.polyml.org/docs/Overview.html . Comments welcome and if anyone with experience with style sheets wants to improve the appearance I'd be happy to include the changes. Ultimately it would be nice to be able to make use of some sort of integrated source/documentation system such as doxygen.
David