MSI desktop motherboard schematic for board MS-7122, with revision 1.00 indicated in the file name. Supplied as a 937 KB PDF, it covers the board circuitry sheet by sheet, from power sequencing and CPU voltage regulation to I/O and memory interfaces. Technicians use it to trace a missing rail back to its source, check expected voltages and look up the values of damaged parts. MSI prints the MS-number on the PCB, so match it and the revision against this document, since layouts differ between versions.
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 .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.