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)