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
American Morse code in Baltimore is on display in the Library of Congress in Washington, D.C. In its original implementation, the Morse Code specification included the following: Various other companies and countries soon developed their own variations of the original Morse Code. Of special importance was one standard, originally created in Germany by Friedrich Clemens Gerke in 1848, which was simpler—it eliminated the long intra-character spaces and the two long dashes—but also included changes in the sequences for eleven of the letters and most of the numerals. The Gerke code had a distinct advantage for use on undersea telegraph cables. Cables suffer from