Leading Mark

a reference point located on a straight line to indicate the direction of movement of a ship or airplane or to mark some boundary. Leading marks may be panels, towers, or lattice masts placed in an open site and painted in a color that contrasts with the background. When necessary, they may be electrically illuminated by equipment that is usually switched on automatically. Two or three leading marks are usually positioned to indicate a waterway on a coast, and at least ten leading marks are used to indicate a landing strip. The locations of leading marks are given on maritime and topographical maps and in sailing directions.