1 MASK
        MASK

    This task masks either the inside or the outside of  a  polygon  in  all
    planes   of  a  data  cube.   It is similar to the MASK command in GreG,
    GRAPHIC or OVERLAY, but it does affect  the  output  image  and  not  an
    internal  copy  of  it.   The  polygon must have been created previously
    using the WRITE POLYGON command in GreG, for example.
2 POLYGON$
        TASK\FILE "Polygon data file" POLYGON$

    This is the name of the polygon file  created  in  GREG  (command  WRITE
    POLYGON).
2 Y_NAME$
        TASK\FILE "Input image" Y_NAME$

    This is the name of the input data cube.
2 X_NAME$
        TASK\FILE "Output image" X_NAME$

    This is the name of the output masked image.
2 MASK_IN$
        TASK\LOGICAL "Mask inside (.true.) or outside (.false.)" MASK_IN$

    Answer YES to mask the inside of the polygon, NO to  mask  the outside.
2 MODIFY$
        TASK\LOGICAL "Modify blanking value" MODIFY$

    Answer YES if you want to change the blanking value, NO if you  want  to
    use that of the input image.
2 BLANKING$
        TASK\REAL "New blanking value" BLANKING$

    This is the blanking value that will be used for the output image.
1 END