APPENDIX I GLOSSARY ABEAM—Bearing 90° or 270° relative from own ship. ACP—Allied Communications Publication. CELESTIAL NAVIGATION—Navigation with the aid of celestial bodies. CLASSIFICATION —The determination that official information requires, in the interest of national security, a specific degree of protection against unauthorized disclosure, coupled with a designation signifying that such a determination has been made. CODRESS —Message having the address buried in the encrypted text. COMMISSION PENNANT—A  long,  narrow, starred and striped pennant flown aboard a commissioned ship. CONVOY—A number of merchant ships or naval auxiliaries, or both, usually escorted by warships and/or aircraft, or a single merchant ship or naval auxiliary under surface escort, assembled and organized for the purpose of passage together. DAYSHAPES —Shapes specified in both International and Inland Rules of the Road to visually indicate particular operations or situations from one vessel to another. DEBARKATION STATION—The place on a ship where personnel assemble to debark in boats. DECLASSIFICATION —The determination that in the interest of national security, some classified material no longer requires any degree of protection against unauthorized disclosure, coupled with removal or cancellation of the classification designation. DEFENSE MAPPING AGENCY—Government agency that produces and sells navigational charts and publications. ENCODE—To convert plain text into unintelligible language, usually word by word, by means of a code book FATHOM—A unit of length equal to 6 feet. FLAGHOIST—A nondirectional means of transmitting signals with predetermined meanings taken from authorized publications. The U.S. and Allied Navies use 68 different flags/pennants or combinations thereof for this purpose. International use consists of 40 different flags and pennants. FLASHING LIGHT—The term applied to the transmission of signals by light. The equipment employed may be directional or nondirectional in operation. The use of directional flashing light reduces the possibility of its interseption, thus providing some security. When security is required at night, only highly directional flashing light should be used and its brilliancy should be the minimum necessary to provide communica- tion. Nondirectional flashing light permits simultaneous transmission to a number of stations in any direction but has little security from interception, particularly at night. FORETRUCK —The highest point of the forward mast. FORMATION—Any ordered arrangement of two or more ships or aircraft proceeding together. FUSELAGE—The body of an airplane. GAFF—A small spar abaft the mainmast from which the national ensign is flown when the ship is underway. GIVE-WAY VESSEL—As directed by Rules of the Road, any vessel required to keep out of the way of another vessel. GNOMONIC PROJECTION—A map projection in which points on the surface of a sphere or spheroid, such as Earth, are conceived as projected by radials from the center to a tangent plane. GREENWICH MEAN TIME—Local mean time at the Greenwich meridian; the arc of the celestial equator, or the angle at the celestial pole, between the lower branch of the Greenwich celestial meridian and the hour circle of the mean sun, measured westward from the lower branch of the Greenwich celestial meridian through 24 hours; AI-1