Break or Union Break Time - SCCS 1.0, is the time between post call and before the SCCS place the set back to an available state for the next ACD call. This is configured within the Call Presentation Class on the client.
i.e., agent x just finished a call, the system placed the set in NRD and start the BREAK TIME timer. When the timer expired the set is placed in the IDLE position, ready for the next call.