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
Comparison of alphabetic country codes least one of these three types of country codes. For a more complete list of countries, see list of countries. The only ambiguous trigraph is "BRN", which stands for Bahrain in IOC code and for Brunei in ISO code. Codes are shown with their last year of use. Comparison of alphabetic country codes This is a comparison of the IOC, FIFA, and ISO 3166-1 three-letter codes, combined into one table for easy reference. Highlighted rows indicate those entries in which the three-letter codes differ from column to column. The last column indicates the number of codes present followed by letters