Sanity check of SVN library interaction

I'm preparing a presentation on Subversion for a local technical
group, and have one slide that is attempting to explain some of the
interaction between SVN components, client and server, especially in
terms of the libraries (libsvn_*). The problem is, I haven't yet found
much documentation about their interaction. (I looked in Chapter 8 of
the book, which describes the functionality of the libraries, but not
precisely who works with whom.)

I've captured what I understood, guessed at what I didn't, and have a
PDF with the results. Specifically, I'm shaky on the file:// access
model, and I'm not sure if any WebDAV clients actually use the
webdav:// schema, so clarification there is especially appreciated.
I'd love to get feedback on how to make this correct without making it
overly complex. I won't be speaking to people who are going to rush
out and tie into the API—I just want to provide a "big picture" of
(roughly) how the system works.

Here is my PDF:

        http://dysart.cs.byu.edu/subversion-libraries.pdf

Text explanations will work fine. If you like, you can mark it up
(preferably digitally) and email me a copy with explanation of why.
Even tips on presentation are welcome. (The slide is built in Keynote,
and I already have animations so it appears in stages.)

Thanks!
  - Quinn