54 STAT.] MULTILATERAL-TELECOMMUNICATION-APR. S, 1938 [375] (2) If, however, even after taking these precautions the emissions of this station should cause interference with a radio trans- mission already in progress, the following rules shall be applied: [376] (a) In the communication zone of a land station open to the public correspondence service or of any aeronautical station, the station whose emission produces the inter- ference must cease transmitting at the first request of the above-mentioned land or aeronautical station. [377] (b) In the case where a radio transmission already in progress between two ships happens to be interfered with by an emission from another ship, the latter must cease transmitting at the first request of either of the other two. [378] (c) The station requesting this cessation must indicate the approximate length of the wait imposed upon the station whose emission it is suspending. [379] §3. Radiotelegrams of all kinds transmitted by ship stations shall be numbered in daily series, assigning number 1 to the first radiotelegram transmitted each day to each land station separately. [380] §4. CALLING A STATION AND SIGNALS PREPARATORY TO TRAFFIC [381] (1) Method of calling The call shall consist of the following: not more than three times the call signal of the station called; the word DE; not more than three times the call signal of the calling station. [382] (2) Wave to be used for the call and for preparatory signals To make the call as well as to transmit preparatory signals the calling station shall use the wave on which the station called is listening. [383] (S) Indication of the wave to be used for the traffic [384] The call, as indicated in subparagraph (1) above, must be fol- lowed by the regulatory abbreviation indicating the frequency and/or the type of wave which the calling station proposes to use to transmit its traffic. [385] When, as an exception to this rule, the call is not followed by the indication of the wave to be used for the traffic: [386] (a) if the calling station is a land station: it shall mean that this station proposes to use its normal working-wave, as indicated in the nomenclature for the traffic; [387] (b) if the calling station is a mobile station: it shall mean that the wave to be used for the traffic is to be chosen by the station called. 1509
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