Paradox alarm
From Jenny Everywhere Wiki
By the First Doctor's day in the 89067986779811167562948736197891674912223184th Universe, one of the standard security alarms within the Old Workshops was a “paradox alarm”. It once reacted to the incursion of Jenny Nowhere and the Great Intelligence, both of whom had come to try and prevent the First Doctor's destiny from occurring; also present was a Junior Time Technician trying to undo the others' interference. (PROSE: How To Steal Timeships & To Influence Time Lords)
