[SIC\]MODIFY VarName|GDFName [/FREQUENCY Linename RestFreq] [/VELOC-
ITY Velocity] [/SPECUNIT FREQUENCY|VELOCITY]
Modify consistently the spectroscopic axis of a lmv cube or a Sic struc-
ture of type IMAGE, HEADER, or UVTABLE.
The spectroscopic axis can be changed to the alternate unit with the op-
tion /SPECUNIT. By default, the unit is unchanged.