Be Unix formatted
"Unix formatted" means two things:
1) Lines must end only with a line feed (LF).
Line feeds are represented as
octal 012 and
Do not use carriage returns (CR)
like Macintosh computers do
or the carriage return/line feed combination
(CRLF) like Windows computers do.
2) There should be one line feed
after the closing PHP tag (?>).
This means that when the cursor is at the very end
of the file, it should be one
line below the closing PHP tag.