Signals for the highway

Our Highway Code has a series of rather pretty illustrations of hand and light signals for drivers (I couldn't find any in the Straßenverkehrsgesetz but it probably has some; if in doubt when driving in Germany, Schrittgeschwindigkeit is the word to bear in mind).
In earlier editions of the British code there was a very fetching line drawing of a man driving a cart, showing him from the back, sitting up in an alert manner as he held his whip aloft, rotating the tip anti-clockwise; I think this indicated that the whole equipage was about to veer to the left, but it may have meant something quite different. Sadly, Google Images could not help with a reproduction.
With regard to flashing headlights, the Highway Code says "Only flash your headlights to let other road users know that you are there", but wisely adds, ..."never assume that it is a signal to go. Use your own judgement and proceed carefully". Yes, indeed, for in my experience the driver is saying either "You stay there, I'm coming through", or "You go first, sweetie", or "You're a dangerous idiot!", or "Watch out, police trap ahead", or (if he's a truckdriver) "It's OK to pull over in front of me now", or (if abroad) "Hi there, compatriot!", or "Did you know your sump's falling off?", or, to the driver behind you,"Good morning, George".