​Doug - that is interesting.  Do you know the time frame of the banishment?  Noel any memories of what allowed it be used?  Clearly, once the restriction was removed, it spread.

At CMU, for the OS course, we had a sign a document with the university stating something that we understood it was AT&Ts IP and we were using it as a teaching tool.  I remember thinking that whole thing was weird, the students could not get accounts on the OS development machines for the course to get get source access -- but I already had one because I was working for the EE dept before I took the official OS course and had been kernel hacking and already helped write fsck with Ted that summer before.  So it felt like the CMU lawyers were trying close the barn doors after they were already open with a couple of us (their were probably 5 or so that were in that same spot).

Maybe if we can find Bill Wulf, whom I think was the one that shepherded that document through the CMU lawyers.  His wife, Anita was teaching the course at the time; IIRC.  He might remember.