CRLF is a word that comes from a mechanical typewriter and is an abbreviation for
Carriage Return and
Line Feed, respectively.
Looking at the ASCII code table etc., it is written as a control code, and the binary value is 0x0D for CR and 0x0A for LF.
Not limited to communication, it indicates the end of a line when displaying text on the screen or inputting from the keyboard, moves to the beginning of the next line, or indicates the completion of command input, and is a delimiter for executing commands.
In the case of text communication, it is often treated as a command input delimiter and execution start.
As for the specifications of communication data, it will be up to the author to indicate such control codes in hexadecimal or abbreviations.
The situation in question is likely to have been abbreviated.
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