Probably to zero out the press point and get an accurate angle. Seems like it's got some spring to it.

Derek Kuraitis they actually scan material thickness and compensates the tonnage for yes an accurate angle but hardly required depending on the quantity and consistency of the blank the parts were cut from.

Raymond Barron Wrong. It's called ACB System. It uses a series of followers on a particular upper tool to measure the angle and the elastic return of the material in order to get a perfect bend that is usually withing +/- 0.3 degrees of the programmed angle. TRUMPF provides upper tools equipped with that system for pretty much all of their series...while it's relatively expensive it's also very useful expecially when paired with a bending robot like the BendMaster 60.