ASCII Gave Printers Separate Commands to Go Left and Down. Your Text Files Kept Them.
RFC 20 defines carriage return and line feed as separate motions, with a combined newline meaning allowed only by agreement.
A carriage return could get you back to the beginning without getting you out of the line you were already on. The printer had obeyed. Your next sentence was still heading for the previous one.
RFC 20 defines CR as moving the printing position to the first position on the “same printing line.” LF advances to the next printing line. Both definitions also cover display devices.
There is an escape clause. LF can mean a complete new line, including the return to the first position, but that interpretation “requires agreement between sender and recipient of data.” Even the newline needed both sides to have the same conversation.
MDN’s CRLF reference gives the modern byte names: CR is \r, hexadecimal 0D; LF is \n, hexadecimal 0A. CRLF puts them together as 0D 0A.
A keyboard key labeled Enter does not tell you which of those bytes an application will store. That part still belongs to the software and the format it is writing.
The next mysterious blank line or stubborn script deserves a look below the text editor’s rendering. A character nobody can see may still be carrying instructions.