UV_FILTER

        [CLEAN\]UV_FILTER [/RESET] [/ZERO] [/CHANNELS Channel_List]
      [/FREQUENCY List Of Frequencies] [/RANGE Min Max [TYPE]]
      [/VELOCITY List of Velocities] [/WIDTH Width [TYPE]]
      [/FILE FileIn [FileOut]]

    "Filter" line emission, by flagging the corresponding channels. The channels
    can be specified either by the /FREQUENCY or /VELOCITY options  in  combina-
    tion  with the /WIDTH option, or by a channel list with /CHANNELS or a range
    (of channels, frequencies or velocities) with /RANGE.

    By default, channels to be filtered are flagged (weights becoming negative).
    Option /ZERO can be used to erase them: weights and visibilities are set  to
    zero,  see  HELP UV_FILTER /ZERO. On the contrary, option /RESET can be used
    to unflag them (and is thus conflicting with option /ZERO).

    The command works on the current UV data, unless the option /FILE is  speci-
    fied.

    With  no  options  (except possibly /FILE and /ZERO), the command behaves as
    UV_FILTER /CHANNELS PreviewChannels. See UV_PREVIEW for details.