Net/2
From Computer History Wiki
Net/2 was the second release of the unencumbered BSD from CSRG.
http://unix-archive.pdp11.org.ru/4BSD/Distributions/Net2/net2.tar.gz
Net/2 is not a usable distribution, but rather as much of the BSD source tree that could be distributed without an AT&T source license. Net/2 was a 4.3 BSD derivative, however it was not a fully functional OS as is.
Some notable Net/2 derived OS's include:
This code release was the basis of the AT&T vs CSRG lawsuit. The CSRG had to withdrawl this software and release the 4.4 BSD Lite which had removed the offending files from the distribution.
Later when Caldera had set the source free for 32v which is the common basis for all AT&T Unix (SYSIII,SYSV), and all of the 32bit BSD releases.
