Schematic for the MSI MS-7673 desktop motherboard, revision 1.0 as indicated by the r10 tag, distributed as a PDF inside a 1.39 MB RAR file. The MS-7xxx code is MSI's own mainboard numbering, found printed on the PCB along with the revision, which should match this document. Technicians rely on such diagrams to trace CPU and memory supply circuits, verify power-good and enable signals in the startup sequence, and pinpoint components near a shorted rail. Any PDF reader handles the extracted file.
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.