So, copyleft and copyright are broken in the same direction, by the same path. If we stop focusing only on copyleft and think about it more generally, the obvious repair path is to not include copyrighted material during training: you simply close off your content — whether copyrighted or copyleft — to machines, and indeed to anyone you do not know. Then you can use what is called attribution-based control, or ABC: an alternative way of training that provides only pointers — a rough idea of what is in a repository — like a library-to-library exchange for books, where the book never leaves your desk. The other library has only an index and a rough sense of the contents； that is all it is allowed.