[flukus]

Also ./ for the current folder is still used on all OS's. I think your examples predate computers having folders though.

[kps]

UNIX's ‘.’ predates Microsoft BASIC. (Possibly inherited from Multics, but I don't know.)

[flukus]

I was thinking more of ed, for some reason I thought folders were a later invention, 70's or early 80's, but they were first used in 1958: https://en.wikipedia.org/wiki/Directory_(computing)