Military Code

a system of conventional symbols for the covert transmission of secret military information through communications equipment.

The conventional symbols are made up by the staff headquarters and may be numbers, letters, and so forth. The simplest military codes are conversation and radio-signal tables made up for a definite span of time or the duration of a combat operation. There are combined-arms and special military codes (for one combat arm or one service of the armed forces, such as an aviation or navy code).