NAME:
  rdsites
 PURPOSE:   (one line only)
  Read an occultation event file
 DESCRIPTION:
 CATEGORY:
  Occultations
 CALLING SEQUENCE:
  rdsites,fn,team,flag,lat,lon,alt
 INPUTS:
  fn - Name of file to read (usually just sites.dat)
 OPTIONAL INPUT PARAMETERS:
 KEYWORD INPUT PARAMETERS:
 OUTPUTS:
  team - Name of team (short string, no blanks)  if there is nothing in the
           file or no file exists, then team=!null and nsites=0
  flag - string, usually one character, meaningful values are:
          y - data are good and constraint the result
          n - There are no constraining data for this site, records attempt
          x - data not yet processed
         other values are ignored
  lat  - Latitute of station in decimal degrees, WGS84 datum
  lon  - East longitude of station in decimal degrees, WGS84 datum
  alt  - Altitude of station in meters relative to WGS84 datum
 KEYWORD OUTPUT PARAMETERS:
  NSITES - number of valid site entries read
 CONFIGURATION:
 COMMON BLOCKS:
 SIDE EFFECTS:
 RESTRICTIONS:
 PROCEDURE:
 MODIFICATION HISTORY:
  Written by Marc W. Buie, Southwest Research Institute, 2022/12/07