docs: def add_linked_station(self, datfile, station, location=None):
          """Add a linked or fixed station"""
          if datfile not in self.fixed_stations:
              self.fixed_stations[datfile] = {station: location}
          else:
              self.fixed_stations[datfile][station] = location
  
          if location and not self.base_location:
              self._utm_zone = location.zone
              self._utm_datum = location.datum
              self._utm_convergence = location.convergence