Ten-coes, properly known as ten signals, are code words used to represent common phrases in voice communication, particularly by law enforcement and in Citizen's Band (CB) radio transmissions. The codes, developed in 1937 and expanded in 1974 by the Association of Public Safety Communication Officials (APCO), allow for brevity and standardization of message traffic. They have historically been widely used by law enforcement officers in North America, although some departments have controversially attempted to prohibit their use.