EMPLOYMENT OF CODES.
Codes are primarily intended for economy, but they may also be readily employed to secure secrecy. When used solely for economy, the coded message is said to be plain code; that is, the word or phrases of the message are coded by direct reference to their respective code equivalents. Thus plain code is readily translatable to anyone in possession of a code book. When secrecy is desired, some method of enciphering or key is employed in such a way that only persons in possession of it can in conjunction with the code book decipher it. In such case the message is said to be in cipher code.