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-3456 Braille pattern dots-3456 The Braille pattern dots-3456 ( ) is a 6-dot braille cell with the top right, middle right, and both bottom dots raised, or an 8-dot braille cell with the top right, upper-middle right, and both lower-middle dots raised. It is represented by the Unicode code point U+283c, and in Braille ASCII with a number sign: #. In unified international braille, the braille pattern dots-3456 is used as a number indicator. † Abolished in Unified English Braille Related to Braille pattern dots-3456 are Braille patterns 34567, 34568, and 345678, which are used in 8-dot braille systems, such as