RAR archive, 886 KB, for the ECS MCP61PM-AM motherboard; neither revision nor contents are stated in the name. Check the revision printed on the PCB and compare it with the material inside after unpacking. The AM suffix separates it from the MCP61PM-GM, so do not swap files between the two. Typical uses are tracing power rails and the power-on sequence on a schematic, locating components behind a short, or reprogramming the BIOS chip after saving its original contents.
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.