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.