I've been there before (admittedly without having looked at all of the 700+ documents), but seem to be unable to find something comprehensive, e.g.
- several dozen documents point to the same three-part open firmware introduction that is targeted at hardware developers and explains how to hook up a 38400 BAUD serial(!) connection;
- one document I found lists "some" of the key-codes that are interpreted by open firmware when pressed during startup, but there is no link to a
complete list of these codes;
- just now I am looking at
http://developer.apple.com/qa/hw/hw38.html which gives a very brief explanation of what a configuration variable is (about as much as I might have guessed anyhow), without pointing to an annotated list of them.
I'll just continue my search...
