 Receivers decode the Morse code to get a sequence of digits, chop it into an array of quadruplets, and then decode them one by one referring to the book.Due to lack of non-digit characters, the Morse codes for digits could be simplified, for example one several consequent dashes could be replaced with a single one.The codebook also defines codes for Zhuyin alphabet, Latin alphabet, Cyrillic alphabet, and various symbols including special symbols for months, days in a month, and hours.