V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

RSTSE
       Resource System Time Sharing/Enhanced (DEC), "RSTS/E"


The Free On-line Dictionary of Computing (30 December 2018):

RSTS/E

    A multi-user, general purpose
   timesharing operating system produced by Mentec, Inc.
   and licensed bu Digital Equipment Corporation.

   RSTS/E can be used for interactive timesharing, batch
   processing, indirect command file processing, program
   development using a variety of languages and tools, and a wide
   variety of special purpose applications.  Up to 127 concurrent
   terminal users in both local and remote locations through
   multi-terminal services can interact with application tasks.
   Without multi-terminal services, 63 users are the maximum.
   Tasks can share computational, storage, and input/output
   services provided by the RSTS/E system.

   Full description
   (http://pyrfect.ico.olivetti.com/SPD/13-01-37.txt).

   (1996-06-04)