First drafted in 1855, this system was first published as an international and a British volume in 1857 and gradually adopted by most seafaring nations. The 1932 revision was published as visual and radiotelegraphy volumes in the English, French, German, Italian, Japanese, and Norwegian languages.

These flags are used at sea for communication between ships. They can spell out short messages and individual flags and various combinations of flags also have special meanings. On ceremonial and festive occasions the signal flags are used to 'dress' (decorate) ships.

Only a few colors can be readily distinguished at sea. These are: red, blue, yellow, black, and white; and these cannot be mixed indiscriminately. You will notice, for clarity, the flags shown are either red and white, yellow and blue, blue and white, or black and white; besides plain red, white, and blue.


Usage:
• One-flag signals are urgent or very common signals (see meanings below)
• Two-flag signals are mostly distress and maneuvering signals
• Three-flag signals are for points of the compass, relative bearings, standard times, verbs, punctuation, also general code and decode signals
• Four-flags are used for geographical signals, names of ships, bearings, etc
• Five-flag signals are those relating to time and position
• Six-flag signals are used when necessary to indicate north or south or east or west in latitude and longitude signals
• Seven-flags are for longitude signals containing more than one hundred degrees.