An adjustable ladder with self-storing features and suitable for installation in the sleeping berth of an over-the-highway tractor. The center sections of the plates are contiguously aligned with opposite parallel surfaces of a center disc. The token count is decremented when packets in the flow are transmitted into the queue, and the token count is incremented at a token increment rate C. Also the supercooled gas is pass across a portion of the media either before or after wet ink received on the medium. The supporting structure is inserted into the pathway and through the plurality of vertebrae.