Ditto for the 386BSD BSD/386 line of  code. I think they were added in the patch-kit phase, not the original Jolitz code phase. FreeBSD 1.0 Beta had them in 1993 for sure, as did NetBSD of the time.

I have a memory of them on 0.98pl13 on Linux as well, but that version sticks in my head as a proxy for anything between 0.96 (the first one I tried) and 0.99 (the last before 1.x Linux). This would be approximately 1992 or 1993.

I've not done the deep-dive into the ancient code bases to see if I can suss out when they arrived.