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

microPLANNER

   A subset of PLANNER, implemented in Lisp by Gerald
   Sussman et al at MIT.  Its important features were
   goal-oriented, pattern-directed procedure invocation, an
   embedded knowledge base, and automatic backtracking.

   microPLANNER was superseded by Conniver.

   ["microPLANNER Reference Manual", G.J. Sussman et al, AI Memo
   203, MIT AI Lab, 1970].

   (1995-01-10)