Not sure which posts you’re referring to, I don’t think my understanding has changed. But I’m going to assume we’re on the same page about the meaning of the second half of the comment   as for the first half of the comment, “gradient of the loss with respect to the output”, is there a general-case interpretation for that as well? I need to use a custom Autograd function that belongs to arbitrary hidden layers, not just output layers. Would it help if I gave some quick backprop formulas so that we could synchronize our language in a formal way?