Telegraphy the sense of a system that can transmit arbitrary messages over arbitrary distances. Lines of signalling relay stations can send messages to any required distance, but all these systems are limited to one extent or another in the range of messages that they can send. A system like flag semaphore, with an alphabetic code, can certainly send any given message, but the system is designed for short-range communication between two persons. An engine order telegraph, used to send instructions from the bridge of a ship to the engine room, fails to meet both criteria; it has a limited distance and
International Code of Signals of case description and treatment. There is also a standard list of medicaments (medicines), keyed to a standard ships medicine chest carried by all merchant ships. The Medical signals all begin with the letter "M" (Mike) followed by two more letters, and sometimes with additional numerals or letters. The International Code of Signals was preceded by a variety of naval signals and private signals, most notably Marryat's Code, the most widely used code flags prior to 1857. What is now the International Code of Signals was drafted in 1855 by the British Board of Trade and published in 1857 as