hey you know, I got my copy of Debian/Gnu Linux 3.0 the other day....maybe I should write SCO's lawyers and ask about licensing terms....
If you do write, make sure you letter is well over 1000 pages long and give strong implications that YOU own some of the UNIX IP (but you're not sure what and you don't intend to tell them), and that you would like SCO to be paying you money... make sure there are several hundred refernces to documents which don't exist, but fully support your case... that should tie them up for a bit while IBM can "be the daddy" :-D
