It's common knowledge that on Windows, a line of text generally ends with a \r\n characters sequence, and on a POSIX system a line of text will end with \n.

Less well known is Perl's support for the escape sequence '\R'.

What's \R?

It's definitely not the inverse of \r.

It's a pattern (so for now its only useful in regexes) that matches Unicode's TR-13, The Unicode Consortium's guidelines for what counts as a newline. It's useful in a regular expression to match \r, \n, \r\…