Which term is used to signal urgency in a communications context?

The term "PAN PAN" is used in communications, particularly in maritime and aeronautical contexts, to signify urgency. It indicates that there is an urgent situation that does not pose an immediate threat to life or property but requires attention. This distinguishes it from "MAYDAY," which is for life-threatening emergencies, and "SECURITE," which is used for safety information that should be transmitted. "ACKNOWLEDGE" is simply a response to confirm receipt of a message and does not indicate urgency. Understanding these distinctions is crucial for recognizing the level of urgency in communication protocols.