Is there a generally accepted set of hand signals for riding in groups, especially in a paceline?

I've seen people put their palms down to the rear or hold up their fist to signal stopping or slowing. Which is correct?

I have have seen people tap their palm against their hip to signal that they done pulling and about to come off the front. Which hip is tapped, the side you are moving toward? I've also seen people flick their elbow or stick out their fingers but that seems less obvious to the riders in the back.

Anything else, or does it vary from place to place?


-Tim-