adj
coded information uses a system of words, letters or symbols instead of ordinary writing so that it can only be understood by someone else who knows the system
　He sent a coded message to CIA headquarters.
having a set of numbers, letters, or symbols to show what something is or give information about it
　The wires are colour coded for easy identification.
coded language expresses your opinion in an indirect way because it will probably offend someone
　They voiced their criticism in coded statements.
technical coded sounds or signals can only be understood by special machines
　coded signals broadcast by the BBC radio transmitters