V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

SCL
       System Control Language


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

SCL

    1. System Control Language.

   2. Symbolic Communication Language.  Designed primarily for
   the manipulation of symbolic formulas.  Featured pattern
   matching (which was partly the inspiration for SNOBOL), string
   operations in buffers, and automatic storage management.  "A
   Language for Symbolic Communication", C.Y. Lee et al, Tech Mem
   62-3344-4, Bell Labs, Sept 1962.