54 STAT.] MULTILATERAL-TELECOMMUNICATION-APR. S , 1938 shall be followed by the word DE and three transmissions of the call signal of the station sending it. It announces that this station is about to transmit a message concerning the safety of navigation or giving important meteorological warnings. [616] (2) In radiotelephony, the word SECURITY (corresponding to the French pronunciation of the word "securit'") repeated three times, shall be used as the safety signal. [617] §27. The safety signal and the message which follows it shall be transmitted on the distress-wave or on one of the waves which, in some instances, may be used in case of distress (see §3 of this article) [Nos. 546, 547, and 548]. [618] §28. (1) In the maritime mobile service, apart from messages transmitted according to a schedule, the safety signal must be trans- mitted toward the end of the first ensuing period of silence (article 21, §5) [No. 492], and the message shall be transmitted immediately after the period of silence; in the cases provided for in article 32, A, §4 (3) and §5 (1), B, §7 [Nos. 741, 744, and 747], the safety signal and the message which follows it must be transmitted with as little delay as possible, but must be repeated, as has just been indicated, at the first ensuing period of silence. [619] (2) All stations hearing the safety signal must continue listen- ing on the wave on which the safety signal has been sent until the message so announced has been completed; they must moreover keep silence on all waves likely to interfere with the message. [620] (3) The foregoing rules shall be applicable to the aeronautical service so far as they are not in conflict with regional arrangements providing aerial navigation with at least equivalent protection. ARTICLE 25 Working Hours of Stations of the Mobile Service [621] §1. (1) In order to permit the application of the rules indicated below regarding the hours of watch, every station of the mobile serv- ice must have an accurate clock and must take the necessary steps to see that it is correctly adjusted to Greenwich mean time (G.M.T .) [622] (2) Greenwich mean time (G.M .T.) (counted from 00:00 to 24:00 o'clock, beginning at midnight) shall be used for all entries in the radio service log and in all other similar documents of ships com- pulsorily equipped with radio apparatus pursuant to an international agreement; the same shall, so far as possible, apply to other ships. A. LAND STATIONS [623] §2. (1) The service of land stations shall, so far as possible, be continuous (day and night). However, the duration of the serv- ice of certain land stations may be limited. Each administration or public enterprise duly authorized to this effect shall determine the service hours of the land stations under its authority. 1549 Ante, p. 1535 . Ante, p. 1525. Post, pp. 1571, 1573. Working hours of stations of mobile service. Land stations.
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