Calling The identity signal of the station(s) addressed is hoisted with the signal. If no identity signal is hoisted, it will be understood that the signal is addressed to all stations within visual signaling distance. If it is not possible to determine the identity signal of the station that it is desired to call, the transmitting station should hoist the group: VF—“You should hoist your identity signal.” CS—“What is the name or identity signal of your vessel (or station)?” At the same time, the transmitting station will hoist its own identity signal. YQ—“I wish to communicate by.. . (Complements table 1, chapter 2) with vessel bearing.. . from me” can also be used. Answering All stations to which signals are addressed will hoist the answering pennant at the dip as soon as they see each hoist (the dip is defined as being one-half the full extent of the halyard). Close up immediately when the signal is understood (closed up is the full extent of the halyard). The answering pennant is returned to the dip as soon as the hoist is hauled down by the transmitting station. How to Complete a Signal The transmitting station hoists the answering pennant singly after the last hoist of the signal, to indicate that the signal is completed. The receiving station will answer this in the same manner as for any other signal. When the transmitting station hauls down the answering pennant, the receiving station will haul down its answering pennant at the same time. How to Act When Signals Are Not Understood You cannot question the meaning of a hoist by displaying the INTERROGATIVE pennant used in naval procedure. If the receiving station cannot clearly distinguish or understand the signal, it keeps the answering pennant at the dip and hoists one of the following signals: ZK—"I cannot distinguish your signal." ZQ—"Your signal appears incorrectly coded. You should check and repeat the whole." ZL—"Your signal has been received but not understood." If the originating ship hoists a wrong signal group, it cannot cancel it with the NEGAT pennant. Although international procedure does not provide for special pennants, it does have signal groups that fulfill the same purpose. In this case, for example, the originating ship would hoist the signal group YN—“Cancel my last signal/message” or ZP—“My last signal was incorrect. I will repeat it correctly.” Substitutes The basic reason for using substitutes in international signaling is the same as in naval procedure: a signal flag can be repeated one or more times in the same group, while the ship may carry only one or two sets of flags. Without substitutes, for instance, it is obvious that such a group as AAA or 1000 can be made only if three sets of signal flags are available. By using up to three substitutes, any two-, three-, or four-letter group can be hoisted with only one set of flags. The FIRST SUBSTITUTE always repeats the uppermost signal flag of that class of flags that immediately precedes the substitute. The SECOND SUBSTITUTE always repeats the second signal flag and the THIRD SUBSTITUTE repeats the third signal flag, counting from the top of that class of flags that immediately precedes them. No substitute can ever be used more than once in the same group. There is an important difference between the use of substitutes in naval and international procedures. As you learned in chapter 5, in naval procedure a substitute repeats ANY flag or pennant that precedes it on the base hoist. In international signaling, a substitute repeats only a flag or pennant of the same class (that is, alphabet or numeral) immediately preceding it. The signal VV, for example, would be made as follows: V FIRST SUBSTITUTE The number 1100 would be made by numeral pennants as follows: 1 FIRST SUBSTITUTE 0 THIRD SUBSTITUTE 6-5