@davel977
I cringe whenever I hear people use the phrase "wrist snap". There is some (moderate) wrist articulation involved. But not what most people would consider a snap. Turning the hand & wrist about the long axis is not a wrist action (articulation).
If it helps DaveL to visualize or think of his hand (& arm) action as a "wrist snap" and it does not result in an overuse injury in the long run, then that is ok for him. But he should not advise others to "snap the wrist" unless he shows them EXACTLY what he means by this misleading term. A majority of students or players will not perform the correct actions if they are given this verbal instruction w/o a proper demonstration of the desired action.
Now to answer your question, BetaServe. Many players will mistakenly interpret a vigorous forearm pronation as a "wrist snap". But there is more to generating RHS during the upward swing to contact that just pronation. As mentioned previously, there is some moderate wrist action. There is radial/ulnar deviation of the wrist. There's also a moderate extension and flexion (not much past neutral). But nothing that most people would consider a wrist snap.
And there's more... shoulder rotation (ISR). Some reputable sources indicate that
ISR might even be a greater contributor to RHS and rotatiion of the hand & racket face than forearm pronation.