I'd bet my next raise it's a signal code of some kind.

By tying the received acoustic signature to the known type of programmed signal code, a specific fish is identified.

He leaned up on his elbow to peer along the road, and sought in his memory for the signal codes.

Nylan hadn't paid that much attention to the signal codes.

And he had given her the ship and the signal code.

Until then, each navy had used its own signal code and operational manuals.

The boy was bright enough, the way he had learned the French signal code in a few hours.

Or then again, they might not even bother with a signal code, and just shoot us out of the skies.

You'll have to buzz the communicator off and on in universal signal code.

Sarazine - girls waving a white handkerchief as a signal code for the army of liberation, played by very young children.