The Free On-line Dictionary of Computing (19 January 2023):

RTS

   1.  run-time system.

   2.  return from subroutine.

   (1999-07-26)


The Jargon File (version 4.4.7, 29 Dec 2003):

RTS
 /R·T·S/, imp.

    Abbreviation for ‘Read The Screen’. Mainly used by hackers in the
    microcomputer world. Refers to what one would like to tell the suit one
    is forced to explain an extremely simple application to. Particularly
    appropriate when the suit failed to notice the ‘Press any key to continue’
    prompt, and wishes to know ‘why won't it do anything’. Also seen as ‘RTFS’
    in especially deserving cases.