SET BLANKING

        [GREG1\]SET BLANKING Bval Eval

    Define a blanking value Bval with tolerance Eval. Default is no blanking
    (i.e.   Eval  negative).  The  blanking  is  used by most curve plotting
    commands such as CURVE, CONNECT, POINTS  to  ignore  data  points  which
    verify  ABS(Y-Bval)  less  or  equal to Eval. The blanking value is also
    used for contours (RGMAP), to avoid plotting contours  in  pixels  whose
    value  verify  the  same  relation  as above. And finally, some commands
    require a blanking value to attribute when they are unable to  define  a
    real value ; this include RANDOM and MASK.