Morse code in Cayo Largo del Sur, Cuba is coded as "UCL", and UCL in Morse code is transmitted on its radio frequency. In some countries, during periods of maintenance, the facility may radiate a T-E-S-T code () or the code may be removed which tells pilots and navigators that the station is unreliable. In Canada, the identification is removed entirely to signify the navigation aid is not to be used. In the aviation service, Morse is typically sent at a very slow speed of about 5 words per minute. In the U.S., pilots do not actually have to know Morse to
Telegraph code limited character set available in Baudot code. Demand for lowercase letters and more punctuation marks led to teleprinters with a 6-bit TeleTypeSetter (TTS) code, and later, 7-bit ASCII code. In 1931, the International Code of Signals, originally created for ship communication by signalling using flags, was expanded by adding a collection of five-letter codes to be used by radiotelegraph operators. Telegraph code A telegraph code is one of the character encodings used to transmit information through telegraphy machines. The most famous such code is Morse code. Morse code can be transmitted and received with very simple electrical equipment, such as