What does "OVER" signify at the end of a radio transmission?

The term "OVER" at the end of a radio transmission signifies that the message is complete and a response is expected. This is a crucial part of radio communication protocols, ensuring that the receiver understands that the transmission has concluded and they can respond accordingly. It's a standard practice in radio etiquette, indicating to the listener that they have the floor to reply.

Using "OVER" helps avoid confusion or interruptions during the communication process. This clear delineation is especially important in high-stakes environments, such as railway operations, where accurate and timely exchanges can affect safety and operational efficiency. The other options involve different contexts or actions in radio communication that do not align with the conventional purpose of using "OVER."