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-25 Braille pattern dots-25 The Braille pattern dots-25 ( ) is a 6-dot braille cell with both middle dots raised, or an 8-dot braille cell with both upper-middle dots raised. It is represented by the Unicode code point U+2812, and in Braille ASCII with the number 3. In unified international braille, the braille pattern dots-25 is used to represent a colon or other punctuation or mathematical operators. Related to Braille pattern dots-25 are Braille patterns 257, 258, and 2578, which are used in 8-dot braille systems, such as Gardner-Salinas and Luxembourgish Braille. In the Japanese kantenji braille, the standard 8-dot Braille