APPENDIX 2 TO ANNEX H OPERATIONS ORDER NO. 2-53. COMMUNICATIONS SECURITY The following material on communications security, based in general on information contained in ACP 125 (A), is published here for the guidance of all personnel and for compliance by those personnel using radiotelephone circuits. 1. The basic radiotelephone procedure prescribed herein shall be used for radiotelephone communications. 2. Classified information will not be discussed over high frequency radiotelephone circuits. 3. Classified information will not be transmitted over very high frequency radiotelephone circuits. 4. Operational Brevity Codes should be promulgated for transmission of classified operational information. Such codes should be submitted to this Headquarters for approval. prior to being placed in use. 5. Communications Security a. In the interest of security, transmission by radiotelephone will be as short and concise as possible consistent with clearness. Since personnel other than trained operators frequently operate radiotelephone equipment, all personnel must be cautioned that transmissions by radiotelephone are subject to enemy interception and therefore have no security. b. Adherence to prescribed procedure is mandatory. Unauthorized departures from or variations in prescribed procedure invariably create confusion, reduce reliability and speed, tend to nullify security precautions, and are prohibited. If the procedure prescribed herein does not cover a specific operating requirement, resorting to initiative and common sense should suffice, ce. The following basic rules are essential to transmission security and shall be strictly enforced on all military radiotelephone circuits. (1) No transmission shall be made which has not been av- (2) The following practices aro specifically forbidden: thorized by proper authority. . (a) Violation of radio silence. (b) Unofficial conversation between operators. (c) Excessive tuning and testing. (d) Transmitting the operator's personal sign or name. (e) Unauthorized use of plain language. He-1 —