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

Symbolic Optimal Assembly Program

    (SOAP) The IBM 650's assembly language.
   "Optimal" refers to rearranging instructions on slowly
   rotating drum memory.

   Versions: SOAP I, SOAP II, CASE SOAP III.

   [Listed in CACM 2(5):16, May 1959].

   (1994-11-04)