Because signals were visible to everyone, including enemies, meanings were often pre-arranged between specific senders and receivers to maintain secrecy. However, several general codes became common:
Report: The History and Application of Smoke Signals The smoke signal is one of the oldest forms of long-distance visual communication, used by diverse cultures throughout history to transmit news, signal danger, or gather people. While often associated with Native American tribes, it has been used by ancient civilizations in China, Greece, and Rome. Historic Use and Origins 1 : Smoke Signal
: Since the 19th century, the College of Cardinals has used smoke to announce election results: black smoke indicates a failed vote, while white smoke signals a new pope. Core Signaling Language Because signals were visible to everyone, including enemies,