A term that means to catch before the handler or Before the trick. This is best illustrated in practice.
A Stall behavior has a Frontside, before the dog lands on the human, and a Backside, after the dog lands on the human. A Frontside Back Stall happens when the dog catches the disc on the way up to the Stall.
The traditional catch for a Stall is a “Backside” catch, meaning the dog has already landed on the handler, and the trick has been done.