It allows process administrator users to undo the execution of tasks workitems from GXflow Client. You can go back, only if all the successor tasks are active. Those successor tasks will be aborted and the undone task will be set to active.
E.g.: you start executing A.
Then B and wait to execute C.
Go to Process - Manager - Process, select the process and clic 'History' button. Then select the B (undoable task) and clic 'Undo' button.