Acknowledgment of receipt.—No message will be considered sent until receipt for the same has been acknowledged. This is effected by making either the "I understand" of the army and navy or the "OK" of one of the Morse systems, depending upon the one authorized. In every case the receiving operator's signal is signed after acknowledgment. When a number of messages are continuously sent, one acknowledgment for all will suffice and will be so understood. In receiving messages nothing should be taken for granted and nothing considered as seen until it has been positively and clearly in view.
Station records.—Records kept at field signal stations will be confined to original files of messages sent and carbon copies of messages received. Ordinarily the only available stationery will be the United States Army Field Message Book. Station records will be invariably preserved as part of the station equipment until orders for their disposition are given by higher authority. Whenever a station is in imminent danger of capture, all records should be destroyed in the discretion and under the direction of the operator in charge.
Formation of signals.—Make signals with regularity; do not send one word rapidly, the next slowly; adopt such a rate of speed as can be read by the distant signaler without causing him to "break" frequently. Make a distinct pause between letters. It is time gained to do so; it is a loss of time and an annoyance to run letters together. Nothing so distinguishes the good from the indifferent operator, visual or telegraph, as this. When signals are being made with a flag, a fraction of a second will be ample. In using the lantern or heliograph, the pause between letters should be relative to the time of display of the elements, longer than with the flag. To prevent any entangling of the flag upon its staff, skillful handling, acquired by practice, is necessary. It is accomplished by making a scoop of the flag against the wind, the movement describing an elongated [figure 8], thus ∞. The motions should be made so as to display in the lateral waves the whole surface of the flag toward the point of observation.
In using the heliograph, if the receiver sees that the sender's mirror needs adjustment, he will turn on a steady flash until answered by a steady flash. When the adjustment is satisfactory, the receiver will cut off his flash and the sender will resume his message.
Repeating the message.—It may happen that very important messages received by signals must be verified by repeating back from the receiving station, signal by signal, each signal used by the sending station in conveying the message. There can be no error in signals thus verified, and the correct transmission of the message is made certain. For such verification each signal must be repeated by the receiving station as soon as it is made at the sending station.
Signal practice.—Full efficiency of the signaler can be maintained only through constant practice, and those in charge of Signal Corps troops should see that sufficient practice be had to insure that accuracy and rapidity in handling messages which is so essential in time of war.
Instruction should commence with the study of the principles of signaling and the theories of their general use, and the pupil should be well grounded in this study before practice is begun. He should so memorize the alphabets to be used that no letter combination will require thought to determine its meaning.
Daily inspections should be made to insure that all signaling instruments, appliances, and materials are in readiness for instant use. Defects in the apparatus annoy the sender; to a greater extent they annoy the person to whom the messages are imperfectly sent, and delays result that may have serious consequences.