SET UNIT

        LAS\SET UNIT Lower [Upper]

    Specify  the  unit  to  be  used for the lower and upper X axis. Allowed
    units are C[hannel], F[requency], [Image] and V[elocity]. Default is Ve-
    locity. For Continuum drifts, this unit is ignored, but the angular unit
    specified by SET ANGLE is used.