Quanta U81 mainboard archive, board number DA0U81MB6C0, revision 1A, totalling 1.40 MB in RAR format, without the laptop brand given in the name. Quanta part numbers start with DA0, then the project code, then MB for motherboard, which helps confirm a match against the label on the PCB. The likely schematic inside is used for tracing power and signal paths, checking for shorts on main rails and finding the EC and SPI flash. Unpack it with an archive tool and confirm the revision letter before relying on component locations.
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.