DuckCorp Dico

Found one definition

1.                 From The Free On-line Dictionary of Computing (19 January 2023):
                   
   
   
                   
                     
   PPN
      Project-Programmer Number.
      A user-ID under TOPS-10 and its various mutant progeny at
      SAIL, BBN, CompuServe and elsewhere.  Old-time hackers
      from the PDP-10 era sometimes use this to refer to user IDs
      on other systems as well.
      [Jargon File]
      (1994-11-18)