Internalised synchronous back-feed reversal loop

An internalised synchronous back-feed reversal loop was a mechanism that the DoctorDonna used in order to prevent the reality bomb from detonating. The DoctorDonna enabled this mechanism from the Crucible's control console. An internalised synchronous back-feed reversal loop was able of closing all Z-Neutrino relay loops. (TV: Journey's End)