Incidentally, I was just reading https://cseweb.ucsd.edu/classes/wi19/cse221-a/papers/bobrow7... about TENEX, which offered roughly the same version numbering facility as VMS, though without the hierarchical filesystem directories VMS and Unix got from Multics. I don't know if TENEX got the idea from an earlier system. They don't mention one.

It's kind of amazing that this one paper introduced command-line completion, copy-on-write pages, load averages, and CAM TLBs.