SET MASK

        LAS\SET MASK [ml1 ml2 [...]] [/VAR array]

    Defines a mask for the Gaussian fits by its  boundaries.  If  available,
    the  cursor  will  be  used  to specify missing arguments, unless option
    /NOCURSOR is present. When using the cursor, enter:  N  (or  Left  mouse
    button) to enter a value, C (or Middle button) to cancel the last entry,
    H for help, E (or Right button) for exit.  The boundaries are in current
    unit.  Default  is no mask. The boundaries are in current unit. See DRAW
    MASK to display the mask(s).

    SET MASK /VAR mask_array
      Define the masks from rank 1 array  mask_array[1+2*NMASK].  The  array
      must be of the following form:
        mask_array[1]=NMASK      number of masks
        mask_array[2*i:2*i+1]    boundaries of mask num. 'i'