Boardview for the K501LX motherboard, revision 2.0, packed in a RAR archive that holds an .fz file. FZ is the encrypted boardview format used for ASUS boards; it opens in viewers such as FlexBoardView, OpenBoardView or BoardViewer. The 193 KB file lets you find part locations, net names and test points on both sides of the PCB while measuring rails or hunting a short. Make sure the board silkscreen shows K501LX rev 2.0, since other revisions can place components differently.
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 @cyberlanelectonik. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.