Nobody's paid to have it pass Open Group Unix Branding certification tests

https://www.opengroup.org/openbrand/register/

so it can't use the UNIX™ trade mark.

But it's got the AT&T Unix kernel & userland sources contained in it.

PDP-11 Unix System III: https://www.tuhs.org/cgi-bin/utree.pl?file=SysIII/usr/src/ut...

IllumOS: https://github.com/illumos/illumos-gate/blob/b8169dedfa435c0...