Archive for the K40AB model with board revision 1.2 stated in the name, about 1.21 MB as RAR. The document type inside is not specified, but the revision tag suggests board-level material such as a schematic. Revision matters: component placement and values can change between versions, so check the revision printed on your PCB before trusting measurements. Use the contents to trace power rails, locate test points and work through shorts. If it turns out to be firmware, back up the chip before programming 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 @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.