We call an "exit" if the BH is poking out with the arrow still inside. We call a "passthrough" when the arrow has completely gone through to the ground. I prefer passthrough because the animal don't freak out and run so far and my arrow usually is not broken, and two holes are unplugged for max bleeding potential.

I call in the dirt a complete pass through and complete penetration when there's two holes, but arrow is still in.

QuoteOriginally posted by Stone Knife:
[QB] When the animal leaves and the arrow does not      

Yup!  

It is not a pass through unless the arrow HAS completely passed through the deer/target, not just penetrated the opposite side.  If the arrow is still in the animal, obviously if has not passed through.  2 holes works pretty well, though.