Source : Free On-Line Dictionary of Computing

Dijkstra's guarded command language
     
         A language invented by {Edsger Dijkstra} ca. 1974.
        It introduced the concept of {guards} and {committed choice
        nondeterminism} ({don't care nondeterminism}).  Described and
        used in ["A Discipline of Programming", E. Dijkstra, P-H
        1976].
     
        (1994-12-07)