On Thu, Jan 23, 2020 at 9:45 PM Warner Losh <imp@bsdimp.com> wrote:
MERT absolutely predates PWB 1.2. MERT has papers starting in 1975 while pwb 1.2  is 1978 or 1979.
I can not say, I have any knowledge so I would trust Rob's sources, but ... I also what I would have thought MERT predates PWB.  Heinz, are you able to illuminate any of these details? 

MERT was V4 while releases of PWB were V6 based. 
I can verify and agree with the later of PWB 1.x being 6th edition, but the MERT tidbit is interesting/thought-provoking. I frankly would have expected the MERT folks to have started with something closer to 5th and then tracked any significant differences as possible.