As used in this part 1513:

  Bed. See Bunk bed.

  Bed end structure means an upright unit at the head and foot of the bed to which the side rails attach.

  Bunk bed means a bed in which the underside of any foundation is over 30 inches (760 mm) from the floor.

  Foundation means the base or support on which a mattress rests.

  Guardrail means a rail or guard on a side of the upper bunk to prevent a sleeping occupant from falling or rolling out.