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  com-
    mands  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 veri-
    fy the same relation as above. And  finally,  some  commands  require  a
    blanking  value  to attribute when they are unable to define a real val-
    ue ; this include RANDOM and MASK.