1-31 Table 1-1.—Table of Equipment Indicators TABLE OF EQUIPMENT INDICATORS Installation (1st letter) Type of Equipment (2d letter) Purpose (3rd letter) Miscellaneous Identification A—Piloted aircraft A—invisible light, heat radiation B—Bombing X, Y, Z—Changes in voltage, phase, or frequency B—Underwater mobile, submarine C—Carrier C—Communications (receiving and transmitting T—Training D—Pilotless carrier D—Radiac D—Direction finder reconnaissance and/or surveillance (V)—Variable grouping F—Fixed ground G—Telegraph or Teletype E—Ejection and/or release G—General ground use I—Interphone and public address G—Fire control, or search- light directing K—Amphibious J—Electromechanical or Inertial wire covered H—Recording and/or reproducing (graphic meteorological and   sound) M—Ground, mobile K—Telemetering K—Computing P—Portable L—Countermeasures M—Maintenance and/or test assemblies  (including tools) S—Water M—Meteorological N—Navigational aids (including altimeters, beacons, compasses, racons, depth sounding, approach and  landing) T—Ground, transportable N—Sound in air Q—Special, or combination of purposes U—General utility P—Radar R—Receiving, passive detecting V—Ground, vehicular Q—Sonar and underwater sound S—Detecting and/or range and bearing, search W—Water surface and under water  combination R—Radio T—Transmitting Z—Piloted and pilotless airborne vehicle combination S—Special types, magnetic, etc., or combinations of types W—Automatic flight or remote control T—Telephone (wire) X—Identification and recognition V—Visual and visible light Y—Surveillance (search detect, and multiple  target tracking) and  control (both fire control and air control) W—Armament (peculiar to armament, not otherwise covered) X—Facsimile or television X—Facsimile or television Y—Data processing