TELECOMMUNICATIO~ COXVENTIOX. DECEMBER~, 1932. well as by aircraft wishing to enter into communication with a coast station or a ship station, shall be the wave 500 kc (600 m) (AI, A2, or B). 2515 [326] (3) The wave of 333 kc (900 m) shall be the international Ante, p. 2481 . calling-wave for aerial services, except as indicated in article 9, §10 (2). [327] (4) The wave of 143 kc (2,100 m) (Type-AI only), shall be the international calling-wave for use in long-distance communica- tions of the mobile service in the band 100 to 160 kc (3,000 to 1,875 m). [328] (5) The wave of 500 kc (600 m) shall be the international distress wave; it shall be used for that purpose by ship stations and aircraft stations in requesting help from the maritime services. It may be used in a general way only for calls and replies as well as for distress traffic, urgent and safety messages, and signals. [329] (6) However, on condition that the distress, urgent, safety, calling, and reply signals are not interfered with, the wave of 500 kc (600 m) may he used: [330] (a) in the regions of heavy traffic for the trans- mission of a single short radiotelegram ; 1 [331] (b) in other regions, for other purposes, but with discretion. [332} (7) Besides the wave of 500 kc (600 m), the use of waves of all types between 485 and 515 kc (620 and 583 m) shall be for- bidden. r33} (8) Except for the wave of 143 kc (2,100 m) the use of any wave between 140 and 146 kc (2,143 and 2,055 m) shall be forbidden. (334) (9) Coast and ship stations working within the authorized band between 365 and 515 kc (822 and 583 m) must be able to use at least one wave besides that of 500 kc (600 m); when an additional wave is printed in heavy type in the nomenclature, this is the normal working-wave of the station. The additional waves thus chosen for coast stations mayor may not be the same as those of ship stations. In any case, the working-waves of coast stations must be chosen in such a way as to avoid interference with neighboring stations. (335) (10) Besides their normal working-waves, printed in heavy type in the nomenclature, land and on-board stations may use, in the authorized bands, supplementary waves which shall be men- tioned in the nomenclature in ordinary print. However, the band of frequencies from 365 to 385 kc (822 to 779 m) shall be reserved to the radio direction-finding service; it can be used by the mobile service, for radiotelegraph correspondence, only subject to the condi- Ani., p. 24lJ3. tions set forth in article 7. I The regions of heavy traffic are indicated in the nomenclature of coast stations. These regions consist of the service areas of the coast stations indicated as not accepting traffic on 500 kc (600 m).
