Programming Language In The Sky. A computational model for concurrency with communication via asynchronous message-passing.
["High Level Programming for Distributed Computing", J.A. Feldman, CACM 22(6):353- 368 (Jun 1979)].
Try this search on Wikipedia, OneLook, Google
Nearby terms: PLisp « PL/I SUBSET « PL/I Subset G « PLITS » PLL » PL/M » PLMK