INTERNATIONAL RADIO CONVENTION. NOVEMBER 25,1927. 2859 (b) If the mobile station can receive the wave indicated it shall send Mobile service pro- •• .' oedure-Contlnued. the letter K. If not, It shall mform the land statlOn by means of the appropriate abbreviation that it is impossible to receive the proposed wave and the two stations shall agree to adopt another working wave. (5) The land station shall continue to use the wave which it has employed until after the transmission of the signal ••• _ • _ (end of work), followed by its call signal. This signal, followed by its call signal, shall be repeated by the mobile station on the international calling wave a.ssigned to its service. (6) When the land station which receives a request to change the type of wave and/or the frequency can not, or does not desire to com- ply with this request, it shall not transmit the signal K, but shall propose, by employing the appropriate abbreviations, the use of another type of wave and/or another frequency. §5. (1) On the wave of 500 kc/s (600 m.) (or on an authorized wave, in the case of communications with an aircraft station), the periods of continuous work between two stations must not exceed approximately ten minutes; after each of these periods a pause must be observed in order to permit, if necessary, another station to send a priority call or to transmit a priority message. (2) On the other waves assigned to the maritime mobile service the length of the period of continuous work shall be controlled by the coast station. In the case of communications between two ship sta~ons, the receiving station shall determine the length of the periods of continuous work. (3) In communications between aircraft stations the length of the periods of continuous work shall be controlled by the receiving air- craft station, subject to the intervention, for that purpose, of the aeronautical station. In communications between aeronautical stations and aircraft stations, the aeronautical station shall control the length of the periods of continuous work. §6. When a station receives a call without being certain that such call is intended for it, it shall not reply until the call has been re- peated and is understood. When, on the other hand, a station receives a call which is addressed to it, but is uncertain of the call sign'll of the calling station, it must answer hnmediately using the signal ••__ •• instead of the call signal of tl:lS latter station. §7. (1) When it is necessary to make test signals in order to adjust the apparatus before proceeding with a call or a transmission, the signals must not be made for more than about ten seconds and they must be composed of a series of V's followed by the call signal of the sending station. (2) If a station sends test signals at the request of another station to permit the latter to adjust its receiving apparatus, these signals must likewise be composed of a series of V's in which the call signal <)f the transmitting station shall appear several times. ARTICLE 10 General can to aU mobile stations §1. Stations desiring to enter into communication with mobile sta- tions, without, however, knowing the names of the mobile stations which are m.thln their range of action, may use the signal of inquiry CQ, in place of the call signal of the station called in the calling formula, this formula being followed by the letter K (general call for all mobile stations with request for reply). §2. In regions where traffic is heavy, the use of the call CQ followed by the letter K shall be forbidden except in combination with urgent signals. General call tc aU mobile stations.
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