A small RAR archive of 25.5 KB whose name, M20, gives no clear indication of the device, board or kind of document inside. The size suggests a compact item such as a firmware fragment, a small boardview or a text note rather than a full schematic set. Before use, extract it and examine the contents with the appropriate tool, and compare any model or board marking found inside against the PCB on your bench. Treat it as unverified until the contents confirm a match with the hardware being repaired.
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 @hrtechno. 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.