Unfortunately, requiring two characters to mark the end of a line <answer>introduces unnecessary complexity and questions as to how to interpret each character when encountered alone</answer>. To simplify matters plain text data streams, including files, on Multics used line feed (LF) alone as a line terminator. Unix and Unix-like systems, and Amiga systems, adopted this convention from Multics. The original Macintosh OS, Apple DOS, and ProDOS, on the other hand, used carriage return (CR) alone as a line terminator; however, since Apple replaced these operating systems with the Unix-based OS X operating system, they now use line feed (LF) as well.
Why is adding two characters at the ned of a line problemsome? 
introduces unnecessary complexity and questions as to how to interpret each character when encountered alone