This blank is four and a half by six and three-quarters inches, including the margin on the left for binding. The back is ruled in squares, the side of each square representing 100 yards on a scale of 3 inches to one mile, for use in making simple sketches explanatory, of the message. It is issued by the Signal Corps in blocks of forty with duplicating sheets. The regulation envelope is three by five and one-fourth inches and is printed as follows:
UNITED STATES ARMY FIELD MESSAGE.
| To | No | |||
| (For signal operator only.) | ||||
| When sent | No | |||
| Rate of speed | ||||
| Name of messenger | ||||
| When and by whom rec'd | ||||
| This Envelope will be Returned to Bearer. | ||||
CHAPTER XII.
SIGNALS AND CODES.
(Extracts from Signal Book, United States Army, 1916.)
General Instructions for Army Signaling.
1. Each signal station will have its call, consisting of one or two letters, as Washington, "W"; and each operator or signalist will also have his personal signal of one or two letters, as Jones, "Jo." These being once adopted will not be changed without due authority.
2. To lessen liability of error, numerals which occur in the body of a message should be spelled out.
3. In receiving a message the man at the telescope should call out each letter as received, and not wait for the completion of a word.
4. A record of the date and time of the receipt or transmission of every message must be kept.