The initials stand for International Association of Lighthouse Authorities, and ‘the’ buoyage system is one result of this group’s efforts to reduce the thirty or so buoyage systems of the world to one uniform pattern. Fully titled IALA Maritime Buoyage System ‘A’, being one of several considered over a period of years, this system is an amalgam of the Lateral and Cardinal systems which were in use by various European countries. System A follows the ‘red to port’. System B has red to starboard, as in (e.g.) US waters. This dictionary is not the right place to give a complete description of the systems – Almanacs and most books on navigation contain full information.