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
Letter beacon in the USSR: The link with the USSR and, more recently, Russia is further supported by the existence of single letter beacons transmitting letters existing only in the Cyrillic Morse code alphabet. The ENIGMA group also accepted these locations for cluster beacons "C", "D", "P" and "S", adding Vladivostok for beacon "F". A recent source (2006) regarding locations was published on the Web by Ary Boender. This publication also contains an extensive list of letter beacon frequencies, both current and historical. The following locations are given for cluster beacons: For solitary beacons and markers, Boender suggests these locations: Transmissions of