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  Create a gamit n-file from the autcln.sum.postfit file
  
  USAGE : sh_sigelv -acmd <afile> -nfile <nfile> -average
  
          <afile> Autcln command file name. [autcln.cmd] 
          <nfile> Name of the n-file to be created. Later read by solve. 
                  N-file name should be of the form (n)(expt)(s).(doy)
                  expt = experiment name, s = session letter, doy = day of year
                  Eg: nigs1c.275 . N-file name used by solve after postfit autcln.
          -sv  option turns on reweighting by satellite (as well as station)
          -average option sets the statistics based on the 25-point average
                  value RMS scatters 
  
  Example : sh_sigelv -acmd autcln.cmd.postfit -nfile nigs1c.278
  
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