Small 996 KB RAR archive named only for the ASUS A3N notebook; no revision, board number or document type appears in the name. Open it with any RAR-capable archiver to see whether it contains schematics, a BIOS image or other service data. Such material for older ASUS laptops is used to trace supply rails, find signals in the power-on chain and identify faulty components. Before relying on it, compare the mainboard revision with the files inside, because ASUS models often had several board 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 @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.