A highly reliable electronic circuit board for suppressing propagation of noise and a power line communication apparatus using it are provided. The distributed file management system includes a central storage device that is communicatively coupled to data repositories configured to store one or more files. A handle section has a bore formed therein for effectively receiving the driver section therein. The shielding tunnel may be connected to the positive and negative supplies in order to provide the required power for the clock repeaters. The packet flow corresponds to a session, and is mapped to at least one session service. A third ferromagnetic layer is positioned adjacent to the spacer for working in conjunction with the second ferromagnetic layer to serve as a free layer.