A Common Transition refers to a Transition that is accessible from multiple stages in the Blueprint.
For example, in a travel management process, the desirable outcome is a "completed trip booking". However, there are chances for the trip to be cancelled at various stages in the process, due to reasons, such as insufficient travel documents or an emergency.
So a transition called "Cancel booking" needs to be made available from multiple points in the Blueprint and such a transition that is made common to a handful of states in Blueprint, is called a Common Transition.
