The board has footprints for a secondary protection circuit. This can be soldered in the available footprint to enable a secondary protection on the board.
The secondary protection circuit footprint is made for a Seiko protection circuit, part number S-8244AAGPH-CEGTFG (4.45V).
The footprint for the fuse is for a Sony fuse with part number SFH-1412A. To solder in this fuse, the track beneath it has to be cut.
The FET for blowing the fuse can be any FET in a SOT-23 package which is rated for the current to blow the fuse. The footprint was made for a PMV31XN FET.
The resistor and capacitor footprints are made for SMD 0402 packaging.