Multics had arbitary "links", which were distinguished from "branches"--the actual file. Links and branches coexisted in directories. Unix was consciously derived from this model, but simplified so that only links have names and branches live elsewhere (the inode list). The architecture is described in http://www.multicians.org/fjcc4.html. This paper is dates from 1964 or 1965; it was certainly authoritative in 1969. I don't know whether it evolved further. Christopher Strachey and Joe Stoy independently conceived a model isomorphic to Unix for OS 6 at Oxford. The two systems were essentially contemporaneous. I am not aware of other systems that allowed multiple names for one file, though clearly the scent was in the air at the time. doug