Roman candle aid to navigation alarm amber light balefire beacon beacon fire bell bell buoy blinker blue peter buoy caution light flare fog bell fog signal fog whistle foghorn glance go light gong buoy green light heliograph high sign international alphabet flag international numeral pennant kick leer marker beacon nod nudge parachute flare pilot flag poke police whistle quarantine flag radio beacon red flag red light rocket sailing aid semaphore semaphore flag semaphore telegraph sign signal signal beacon signal bell signal fire signal flag signal gong signal gun signal lamp signal light signal mast signal post signal rocket signal shot signal siren signal tower spar buoy stop-and-go light the nod the wink touch traffic light traffic signal watch fire white flag wigwag wigwag flag wink yellow flag