I'm not a lawyer, and only a lawyer can give you a definitive answer to the question. If you copyright a script, and someone steals it, all you have to show is that the resemblence between your copyrighted script and the stolen version is "substantial". Format doesn't count. On the other hand, a bare "idea" doesn't count, either, as the man discovered who pitched a "Superman ends war" idea to Christopher Reeve. On the other hand, Hollywood lawyers have deep pockets, and there are many stories of people who were in the right loosing because they couldn't keep up the legal fees. Outside of Hollywood, writers don't have much to worry about, but Hollywood is a world unto itself.
This is the race that will rule the sevagram!