UNIX trademark registration

[gwyn at BRL-TGR.ARPA]

If you have access to source code for ANY version of UNIX, you are
supposed to be bound by your site's license agreement with AT&T.
That is what keeps UNIX a trade secret.  Certainly, UCB can add
their own restrictions for their enhancements ON TOP of AT&T's.

For a UNIX look-alike to be free of AT&T ownership, it would have
to be developed entirely from publicly available information.
Although this covers a lot of ground, that is still so much work
that only a few vendors offer such systems, and they are hard put
to track newer developments of the "official" UNIX product.