Archive of service documentation for the MSI X299 GAMING PRO CARBON AC, an HEDT board identified in the name as MS-7A95 revision 1.0. The 3.46 MB RAR probably contains schematic pages for the X299 platform board. Repair work on these boards often centres on the multi-phase CPU VRM, the DIMM rails for both memory banks and the standby supply to the chipset, and the diagrams show where each rail originates. Check that the PCB revision silk-screen says 1.0, and open the extracted PDF with any ordinary viewer.
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 @IT_SERVICE_WORLD. 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.