15.64.46  REVISION 

     SET REVISION=n.m
Sets the current revision level.  This affects the operation of TOPDRAWER.
By lowering the revision level you may return to old  behavior.   Some  of
the old revision levels are:
  *  1.0 - Original version
  *  2.0 - SET THREE THETA modified to conform to documentation.
  *  2.2 - X= SET=n FROM=n1 TO=n2...  Worked incorrectly if n>1.