Service package for the ASUS X550WE motherboard, revision 1.3, stored as a 1.10 MB RAR archive. The name gives no details of the contents, which commonly are a circuit diagram and occasionally a boardview file. After extracting, you can trace signal lines, check the power-on sequence and locate parts on the board when diagnosing faults. Since a 2.0 revision of this model is also around, compare the revision silkscreen on the PCB with this one first, as layout and part designators may change between revisions.
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 @alischematics. 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.