Morse code was later made the standard by the International Telecommunication Union (ITU). Morse's original code specification, largely limited to use in the United States and Canada, became known as American Morse code or "railroad code". American Morse code is now seldom used except in historical re-enactments. In aviation, pilots use radio navigation aids. To ensure that the stations the pilots are using are serviceable, the stations transmit a set of identification letters (usually a two-to-five-letter version of the station name) in Morse code. Station identification letters are shown on air navigation charts. For example, the VOR-DME based at Vilo Acuña Airport
American Morse code shorter dash, leads to the advantage of a more compressed code and a faster sending rate. The same operator could send at least 20% faster with American Morse than with International Morse. The greater complexity of American Morse meant that it was easier for operators to make errors. American Morse has multiple lengths of dashes and spaces and inadvertently transmitting the wrong ones and other timing errors by novice operators is known as hog-Morse. Over time, with the disappearance of landline telegraphy, and the end of commercial radio use of Morse Code, American Morse has become nearly extinct in some