Software applications and operating systems have various conventions for representing the end of a line of text, the so-called newline. This term, to be distinguished from "new line", is used for a code in a text to go to a line, as opposed to a new line that is the result of automatic wrapping by the program that displays the text. It is done with one or two control characters. Most systems use either LF (Line Feed) or CR (Carriage Return) individually, or CR followed by LF. When an OS stores text in a file using ASCII or an ASCII-compatible 8-bit encoding, as is typically the default, these characters are represented with their single ASCII bytes 0A, 0D, or 0D followed by 0A, respectively. (In the 1958 version of ASCII, for which Multics was originally designed, there was a separate newline (NL) character in addition to CR and LF. The 1963 revision combined NL with LF, and Multics followed suit. Unix followed the Multics practice, and later systems followed Unix.)
Some mainframe operating systems still use EBCDIC, an IBM-proprietary 8-bit encoding that is completely incompatible with ASCII. In EBCDIC, the "Next Line" (NEL) code at X'15' is the typical end-of-line character. The following table demonstrates the variations in the end-of-line conventions among OSes:
In the C standard I/O library, files can be accessed in either "text" or "binary" mode; when performing input or output in text mode, on a system where lines are not terminated by the C newline character '\\n', the native line termination is automatically translated into a C newline. (This is a legacy of C's historic grounding in Unix, where there is no need for such a distinction.)
NEL:
CRLF: