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
Braille pattern dots-1 Braille pattern dots-1 The Braille pattern dots-1 ( ) is a 6-dot or 8-dot braille cell with the top left dot raised. It is represented by the Unicode code point U+2801, and in Braille ASCII with "A". In unified international braille, the braille pattern dots-1 is used to represent open, unrounded vowel sound, like /æ/ or /ɑ/, such as the Latin letter A, Greek alpha, Cyrillic А, Hebrew/Arabic aleph, etc. It is also used to signify the number 1. Related to Braille pattern dots-1 are Braille patterns 17, 18, and 178, which are used in 8-dot braille systems, such as