Morse code thus determines the dot length. It is common to assume that a word is 5 characters long. There are two common typical words: "PARIS" and "CODEX". PARIS mimics a word rate that is typical of natural language words and reflects the benefits of Morse code's shorter code durations for common characters such as "e" and "t". CODEX offers a word rate that is typical of 5-letter code groups (sequences of random letters). Using the word PARIS as a standard, the number of dot units is 50 and a simple calculation shows that the dot length at 20 words per minute
Prosigns for Morse code efficient telegrapher/telegraphist. The procedure signs below are compiled from the official specification for Morse Code, ITU-R M.1677, International Morse Code, while others are defined the International Radio Regulations, including ITU-R M.1170, ITU-R M.1172, ITU-R M.1677-1, and the International Code of Signals, with a few details of their usage appearing in ACP-131, which otherwise defines operating signals, not procedure signals. For the special purpose of exchanging ARRL Radiograms during National Traffic System nets, the following prosigns and signals can be used, but many of them do not have equivalents in any other definition of Morse code signals, including the ITU-R and