N55SF main board boardview, revision 2.0, a 136 KB .fz file; MB in the name marks it as the mainboard rather than a daughterboard. A boardview viewer such as OpenBoardView or FlexBV displays component locations and nets for finding parts, probing rails and checking pin continuity. It is most useful alongside a schematic of the same board. The .fz format is typical for ASUS boardviews. Confirm the revision printed on your board is 2.0, otherwise component references may not line up.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @pepeelectronica. Enginerys does not host this file.
How to open a .fz file
Compressed and encrypted boardview used for ASUS, ASRock and Pegatron boards.