Abstract: An automated library which handles cartridges of information storage media includes a magazine (40) which comprises a cartridge engaging member (1428) which deflects to preclude insertion of the magazine into a magazine cavity (840) in the library frame (36) when the cartridge is improperly inserted into the magazine. The magazine defines a cell for the cartridge and comprises a magazine wall (1420) from which cell partitions (1410) extend. The cartridge engaging member (1428) is a cantilevered arm having a distal end extending in a direction into which the cartridge is insertable into the cell, and has a cartridge engaging profile whereby, when a cartridge (C) is properly inserted into the cell, the cantilevered arm does not extend beyond a reference plane but when the cartridge is not properly inserted the cantilevered arm deflects beyond a reference plane.