The rack consists of a plastic box, fan motors and a backplane PCB. Since
the rack is provided with built-in fan motors, it does not require the
external air flow conditions described in Section 3.5. The air comes into
the rack from the bottom and goes out through the fan motor, which is
located on the top of the rack. Space as shown in below must be reserved
not to disturb the air flow (, )
The backplane PCB, which is located on the rear side of the rack,
interconnects the PCBs installed in the rack.