Source : Free On-Line Dictionary of Computing

Official Production System
     
         (OPS) The first {production system} (i.e. rule
        based) programming language, developed at {CMU} in 1970 and
        used for building {expert systems}.  OPS was originally
        written in {Franz Lisp} and later ported to other {LISP}
        dialects.
     
        (2003-04-05)