ASUS X540SA archive, an 867 KB RAR carrying the RG tag, which in ASUS naming usually marks the board revision release without giving the number. The name does not specify the contents, so check after extracting whether it holds a schematic, a boardview or both. Schematics for this model serve tracing of charger, standby and main rails, while a layout helps locate components and test points physically. There is an identically sized duplicate in the index. Match the revision printed on the PCB to the document before relying on it.
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 @cyberlanelectonik. 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.