I've never marked my shafts, but it's only because usually after time, I can pretty much tell by feel/appearance which of my shafts is my main and my spare. But it's pretty common to mark the inside of the joint area with a felt pen or something similar for those that risk confusing the two.
As far as marking where your pivot point is on your shaft, that's up to you as a personal choice. Although I'm not a 'pivot point' player, I'm of the belief that over time, your body (muscle memory) tells you where your pivot point is, so looking for a certain mark on your shaft while you're in the shooting position is just another un needed distraction.
dave
I am with you Dave, I am not the Pivot kinda guy either!!!!!!