Is it ensure, insure, or assure?
(EOL) Synonym for newline, derived perhaps from the original CDC 6600 Pascal. The abbreviation "EOL" is now rare, but widely recognised and occasionally used for brevity. Used in the example entry under BNF.
Out of context this would probably be (deliberately) ambiguous because different systems used different (combinations of) characters to mark the end of a line. Unix uses a line feed; DOS uses carriage return, line feed (CRLF) and the Macintosh uses carriage return.
See also EOF.