Worth mentioning that we're actually talking about different types of properties here, but having said that: it does get blurrier than that. If I write a helper library, that's my code. My subsequent modding may call my library. Its easy enough to call my modding communal piracy, and I don't even strongly argue with it. But the mod may end up being 50% library-work, and that library might get used in tons of stuff that has nothing to do with the mod.