I believe "brevity codes" such as
Charlie and
Roger are a spin-off of the equivalent telegraphy brevity codes, because of course telegraphy preceded voice radio communications.
- Roger => voice = "received," but it never, ever means "affirmative" or "yes," though we have all heard this incorrectly used for that.
- R => Telegraphy = "received," but it never, ever means "affirmative" or "yes" ...
- Charlie => voice = "correct"
- C => Telegraphy = "correct"
Brevity codes
Note: I learned and used telegraphy starting in 1962 as a teen, and was a CW/telegraphy operator in the USN, back when ships were made of wood and sailors were made of steel.
