Flag Semaphore

A visual signalling system in which a person holds two flags at prescribed angles to represent characters and procedural signals.

Letters are formed by combinations of the two arm positions. Numerals reuse selected letter positions after a Numbers Follow signal, while separate signals control readiness, spacing, errors and cancellation.

Semaphore requires a clear line of sight, correct viewing orientation, deliberate pacing and acknowledgement. It can supplement other communications but is limited by darkness, visibility, distance and the receiver’s training.