CATLAM

  1. port-hand lateral mark: indicates the port boundary of a navigational channel or suggested route when proceeding in the 'conventional direction of buoyage'.
  2. starboard-hand lateral mark: indicates the starboard boundary of a navigational channel or suggested route when proceeding in the 'conventional direction of buoyage'.
  3. preferred channel to starboard lateral mark: at a point where a channel divides, when proceeding in the 'conventional direction of buoyage', the preferred channel (or primary route) is indicated by a modified port-hand lateral mark.
  4. preferred channel to port lateral mark: at a point where a channel divides, when proceeding in the 'conventional direction of buoyage', the preferred channel (or primary route) is indicated by a modified starboard-hand lateral mark.
Note: the 'conventional direction of buoyage' may be either the general direction taken by the mariner when approaching a harbour, river, estuary or other waterway from seaward, or the direction determined by the proper authority, which in principle follows a clockwise direction around land masses.