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
History of the Arabic alphabet a dot below = "i", a dot on the line = "u", and doubled dots giving "tanwin". However, this was cumbersome and easily confusable with the letter-distinguishing dots, so about 100 years later, the modern system was adopted. The system was finalized around 786 by al-Farahidi. Before the historical decree by Hajjaj ibn Yusuf, all administrative texts were recorded by Persian scribes in Middle Persian language using Pahlavi script, but many of the initial orthographic alterations to the Arabic alphabet might have been proposed and implemented by the same scribes. When new signs were added to the Arabic alphabet, they