"Open" was certainly not a work heard in the Unix lab,
where our lawyers made sure we knew it was a "trade secret".
John Lions was brought into the lab both because we admired
his work and because the lawyers wanted to reel that work
back in-house.
Out in the field, the trade secret was treated in many
different ways. Perhaps the most extreme was MIT, whose
lawyers believed it could not be adequately protected in
academia and forbade its use there. I don't know what
eventually broke the logjam.
Doug