1) Disengagement 2) Plan b 3) Pullout 4) Retreat 1) Pullout 
Fallback is a contingency option to be taken if the preferred choice is unavailable. It may specifically refer to: == Other == ...
A transaction that is verified by a method other than the optimum available on both the card and the device. In a maturing chip and PIN environment, fallback to signature, key entry or paper will be actively discouraged and will eventually disappear altogether.