Boardview for the ASRock B85 PRO4 desktop motherboard, revision 1.02, provided as a 776 KB ZIP. B85 indicates the Intel chipset of this board. A boardview shows the physical placement of components and their net connections, which helps when locating a shorted MOSFET, measuring VRM rails or finding a missing resistor. Extract it and open it with a boardview program such as OpenBoardView or FlexBV. Make sure the revision printed near the PCIe slots or board edge matches 1.02 before relying on it.
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 @zinfo_desktop. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.