Source : Free On-Line Dictionary of Computing

QPE
     
        Two-dimensional pictorial query language.  "Pictorial
        Information Systems", S.K. Chang et al eds, Springer 1980.
     
        Q-systems.  A. Colmerauer, 1969.  A rewrite system with
        one-way unification, used for English-French translation.  It
        led to Prolog.  "The Birth of Prolog" A. Colmerauer et al,
        SIGPLAN Notices 28(3):37-52 (March 1993).