In communication over two-way radios, in use by the military, police and fire despatching systems, and CB radio, what does "over" mean?
I have finished talking and I am listening The traditional, in film and TV, phrase "over and out" is a contradiction since "out" means "end of conversation", i.e. "over and out" means "over to you but I won't be listening".
What is the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message?
