I have a question: when you mean photo manipulation does that include digital editing (lights, shadows, resize) or does it refer to "photoshop-like" total transfiguration? Also, when you say it has to be credited, is it okay for the model in question to be credited with editing, even if the photographer is credited as a different person?
I'm a "newcomer" I'm afraid so I'm terribly sorry to bother with all these questions.