RAR archive of 1.66 MB for board code 3D1-68GT with the suffix R10, most plausibly revision 1.0. The name gives no description of the contents, so extract it with 7-Zip or WinRAR to find out whether it is a schematic, boardview or firmware image. Before tracing signals or measuring rails against it, match the code and revision printed on the PCB. A related 3D1-20 package exists, and similar codes should not be treated as interchangeable without checking.
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.
7-ZipWinRARThe Unarchiver (macOS)