Prosigns

Prosigns, or procedural signals, are compact signals used in radiocommunications to convey instructions or structural cues rather than letters. They are typically two-letter combinations or single characters that function as shortcuts for actions such as starting or ending a transmission, separating sections, or indicating when a response is expected. Prosigns are transmitted as a single Morse element or with unusually tight spacing, and they help operators manage the flow of a message without long written text.

The set and meaning of prosigns vary by service and era. They were widely used in Morse code operations, including maritime, military, and amateur radio environments, and they remain a recognizable feature in historical manuals and in some current hobbyist practice. Because they are operational rather than linguistic, different organizations and national administrations may adopt different signs or emphasize different usages.

Common examples (where used) include signs that indicate the end of a message, a break between text segments, or a courteous close to a contact. In practice, operators learn a subset relevant to their operating context and may encounter additional prosigns in older manuals or specialized fleets. Modern digital protocols often replace the explicit use of prosigns with explicit commands, but the underlying concept—signal meaning through concise, non-letter codes—persists in various forms of radio communication.

See also: Morse code, procedural signals, amateur radio, maritime radio, military communications.