foul tip / foul ball

[Buckeye12]

I was wondering what the exact criteria is to denote a foul tip from a foul ball. The instance I'm particularly interested in is when the batter fouls a ball behind the catcher. Is there a certain height that the ball must reach in order for the catcher to catch it for an out.

I know that a foul tip goes directly from the batters bat to the catchers glove. This still applies if the ball hits the bat, glances off the catchers glove hits the catchers mask, goes in the air and is then caught. What happens if the ball would come off the bat, hit the catchers mask, go straight up and then caught. Is this an out. I hope this isn't too confusing.

So in summary, I'm looking for information on how to call a foul ball from a foul tip.