Close. It’s ANSI/POSIX Environment. It’s been there since Plan 9 second edition. I think it was put there basically for TeX, but don’t quote me on that because

Close. It’s ANSI/POSIX Environment. It’s been there since Plan 9 second edition. I think it was put there basically for TeX, but don’t quote me on that because I no longer remember where I read that and it isn’t in the original paper. http://doc.cat-v.org/plan_9/4th_edition/papers/ape http://doc.cat-v.org/plan_9/4th_edition/papers/ape