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
Morse code abbreviations Morse code are formed. From 1845 until well into the second half of the 20th century, commercial telegraphic code books were used to shorten telegrams, e.g. "Pascoela = Natives have plundered everything from the wreck". The following Table of Morse code abbreviations and further references to Brevity codes such as the Q code, Z code and R-S-T system serve to facilitate fast and efficient Morse code communications. To make Morse code communications faster and more efficient, there are many internationally agreed patterns or conventions of communication which include: extensive use of abbreviations, use of brevity codes such as the RST