; CHANNEL
;---------------------------------------------------------------
;! sets the spectral channel number
;# ADVERB SPECTRAL
;-----------------------------------------------------------------------
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;-----------------------------------------------------------------------
CHANNEL   LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC
----------------------------------------------------------------
CHANNEL
Type:  Adverb  (scalar)
Use:   To set a single, usually spectral, "channel" number, where the
       definition of channel will depend on the particular verb or task.
Null value:
       0   => continuum, all, or 1 depending.
Procedures:
   LINIMAGE....Build image cube from multi-IF data set.  CHANNEL is
               passed to IMAGR.
   MAPPR.......Simplified access to IMAGR.  CHANNEL is passed to IMAGR.
Tasks:
   AVSPC.......Averages uv spectral channels; CHANNEL is number to
               average together
   FRMAP.......Build an image using fringe-rate spectra; CHANNEL is the
               reference channel.
   IMAGR.......Images and Cleans uv data; CHANNEL is the restart
               spectral channel.
   IMERG.......Merges images of different spatial resolutions.
               CHANNEL selects the plane number.
   OOSUB.......Subtracts/divides a model from/into a uv data base
               CHANNEL selects a single channel to be changed.
   PRTSD.......Prints single-dish data.  CHANNEL selects the first
               spectral channel to be printed.
   PRTUV.......Prints uv data.  CHANNEL selects the first spectral
               channel to be printed.
   SDLSF.......Least squares fit to channels and subtracts from SD uv
               data.  CHANNEL selects the frequency of the fit to be
               output in a uv data set.
   SPLAT.......Applies calibration and splits or assemble selected
               sources.  CHANNEL sets number spectral channels
               averaged in one of the averaging options.
   UVADC.......Fourier transforms a Clean point model and corrects for
               geometric distortions and adds to a uv data set.  CHANNEL
               selects the spectral channel to be altered.
   UVDIF.......Prints differences between two uv data sets.  CHANNEL
               sets the first spectral channel printed.
   UVFND.......Prints data found by various criteria.  CHANNEL sets the
               first spectral channel to be examined and printed.
   UVLSD.......Fits continuum to uv spectral data and divides by it;
               CHANNEL selects a channel at which the fit is output.
   UVLSF.......Fits continuum to uv spectral data and subtracts it;
               CHANNEL selects a channel at which the fit is output.
   UVMAP.......Fourier transforms uv data to make an image and beam.
               CHANNEL selects the spectral channel to be imaged.
   UVPRM.......Measures uv range, total flux, observing time, reference
               antenna from a uv database.  CHANNEL selects the spectral
               channel at which the parameters are found.
   UVPRT.......Prints uv data, optionally with calibration.  CHANNEL
               sets the first spectral channel printed.
   UVSUB.......Subtracts/divides a model from/into a uv data base.
               CHANNEL selects a single channel to be changed.
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