To Nod or Not to Nod

I just read about the not nodding boot'n scoot'n riders, a recent Sydney Knights post.

So, I have been wondering about the Nod-etiquette. Is there a NOD-secret convention?

Like squeezing along a row of theatre seats when you have arrived late. Pointing your bum towards another patron's face is considered rude by some.

So, what's the story with the nod?
Chin towards the other rider?
Chin away from the other rider?
Chin straight down or straight up?

What about groups...only greet the leader, Kawasaki riders or (insert your favourite brand here) riders?

What about when you are riding in a group yourself? Should every rider nod or does the leader do it for you?
... just a thought! Not paranoid at all...

...just about to 'nod off'...