RAR archive, 483 KB, covering the MSI MS-6506 board at revision 1.0. The name identifies manufacturer, model code and revision, but not whether the contents are schematics or firmware. A separate 0A revision of this board also exists, so compare the revision silkscreened on the PCB before trusting part references. Technicians use such material to follow voltage regulators and chipset signals or to restore a damaged BIOS with a programmer, after first reading and saving the original chip.
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.