This records the name of the previous stage the state machine on this object was in, immediately before its current stage. Deleting a QoS definition isn't instantaneous — UCS Manager has to unwind every reference to it on every fabric interconnect and adapter that used it, and this task object is what tracks that cleanup to completion. For example this might read 'ConfigFabricA', letting an admin reconstruct the sequence of steps the workflow already passed through even if the FSM has since moved on.