The Signal Bridge was a platform high in the superstructure of a ship where all visual signaling took place, including flag hoist, semaphore, and flashing light. Signal flags were flown from the mast in letters or codes assembled into messages for other U.S. Naval ships or allied forces. Semaphore used hand-held flags that a signalman employed to spell out words or codes, while flashing light used the Morse Code alphabet. A signalman also played a major role in identifying unknown ships in the area.