PV

        SHOW PV [[VarName] Axis Offset]

    Extract from the indicated 3-D SIC variable a Position-Velocity image at the
    specified  Offset (in arcsec) along the specified Axis (X or Y), and display
    it.

    The data cube variable name VarName is optional: the  last  displayed  among
    SKY, CLEAN and DIRTY data cubes are used in this priority order.

        SHOW PV

    will  simply  redisplay  (with  different  controls, see SHOW PV ? to have a
    list) the last extracted Position-Velocity image.