A complete system of crypto-communications between two or more holders. The basic unit for naval cryptographic communication. A cryptochannel is analogous to a radio circuit. It includes: (a) The cryptographic aids prescribed. (b) The holders thereof. (c) The indicators or other means of identification. (d) The area or areas in which effective. (e) The special purpose, if any, for which provided. (f) Pertinent notes as to distribution, usage, etc.