It is possible for a piece of software to rely on the output of another piece of software without being derivative. Hell, that's basically how any interface in

It is possible for a piece of software to rely on the output of another piece of software without being derivative. Hell, that's basically how any interface in the world works. As the wikipedia article on the GPL notes, the problem is not so much the GPL, but how derivative work is not that well pinned down in copyright law itself. That it appears ambiguous in the GPL is a result of that. My rule of thumb is to approach it from the angle of "what is the software worth if you take out what is linked?" - If the software can function without the linked code, it may not be derivative, but the actual question is whether it is useful without the linked code. Whether it carries out the tasks that the user needs the software for without the linked code. To me, it's more of a social question of how much the linkee is indebted to the linked. So no, I don't think I am confusing the two. https://en.wikipedia.org/wiki/GNU_General_Public_License#Linking_and_derived_works https://en.wikipedia.org/wiki/GNU_General_Public_License#Lin...