How did TOPS-10 handle directories? The article says "Note that the odd numbers in square brackets [27,5434] are the TOPS-10 way of specifying directories," but doesn't give any more detail.
I am shamelessly uninterested in poring over the linked TOPS-10 manual to find out, so I'm hoping you know. :D
The numbers are a "project programmer number", or PPN. The "project number" is like a bit like a GID, and the "programmer number" identifies the user within the project (so a bit like a UID).
A lot of early operating systems didn't have hierarchical directories. It was common to have either one single directory for the whole volume (like CP/M and DOS 1.0 had), or else a two-level structure in which each user gets their own directory but no nesting of directories is allowed. TOPS-10 PPN's are like that.
I am shamelessly uninterested in poring over the linked TOPS-10 manual to find out, so I'm hoping you know. :D