15.78.14  MINUS 

Subtracts  the value from the coordinate or the coordinate from the value.
If you specify ERROR and you are subtracting a constant to X,Y, or  Z  the
DX,DY,  or  DZ  are  also  modified.  DY=SQRT(DY**2+(e)**2) where e is the
specified error.
                                  example
To subtract 2+-0.1 from y
     Y=Y MINUS 2 ERROR=.1
          or...
     Y=Y - 2 ERROR=.1
To subtract Y from 2.
     Y=2 MINUS Y
          or...
     Y=2 - Y