Rar archive of 236 KB for the Y61-MB-D motherboard, revision D, apparently a companion of the matching boardview file. No brand, model or chipset is given in the name. Layout data of this kind lets a technician pinpoint components, connectors and test points while diagnosing no-power or short conditions. Extract and open the content with a boardview program, and check the silkscreen reads Y61 revision D, since the E revision of the same board has its own 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 @SCHEMATICWORLD. 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.
7-ZipWinRARThe Unarchiver (macOS)