Morse code encoded the same way (A, O, E, I, T, M, N, R, K, etc.). Bulgarian alphabet contains 30 characters, which exactly match all possible combinations of 1, 2, 3, and 4 dots and dashes. Russian requires 1 extra character, "Ы" which is encoded with 5 elements. During early World War I (1914–1916), Germany briefly experimented with 'dotty' and 'dashy' Morse, in essence adding a dot or a dash at the end of each Morse symbol. Each one was quickly broken by Allied SIGINT, and standard Morse was restored by Spring 1916. Only a small percentage of Western Front (North Atlantic
SOS CQD appears to have died out thereafter. In both the 1 April 1905 German law and the 1906 international regulations, the distress signal was specified as a continuous Morse code sequence of three dots / three dashes / three dots, with no mention of any alphabetic equivalents. However, in International Morse, three dots comprise the letter ""S"", and three dashes the letter ""O"". It therefore soon became common to refer to the distress signal as ""S O S"". An early report on The International Radio-Telegraphic Convention in the 12 January 1907, "Electrical World" stated that "Vessels in distress use the