(1) If a disaster drill is signaled, the signal must be sounded on the disaster alarm system and not on the signal system used to dismiss classes.
(2) The recall signal must be separate and distinct from any other signal. The recall signal may be given by distinctive colored flags or banners. If the recall signal is electrical, the push buttons or other controls must be kept under lock and the key kept in the possession of the principal or some other designated person in order to prevent a recall at a time when there is a disaster. Regardless of the method of recall, the means of giving the signal must be kept under lock.