A schematic diagram for MSI hardware (board MS-7409). Shared as “ms-7409-2.0.pdf” — a .pdf file, 837 KB.
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 @schematics_bios. 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.