It's valid for when there's a previous version there for your target distro/version. e.g. for ubuntu raring there's a CodeLite 5.1, so:
deb http://repos.codelite.org/ubuntu-5.1/ raring universe
should work (if you're using raring and it fails, please tell me!).
However there isn't a raring 5.0 (raring wasn't released then) so writing ubuntu-5.0 won't work for it; it will for quantal though.