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.