Compressed RAR package, 332 KB, labelled for the P7H55-M SI motherboard, an H55-chipset desktop board model following ASUS naming. Nothing in the name specifies the document type, so open the archive to see whether it holds a boardview, schematic pages or another repair file. Sizes in this range often correspond to boardview data usable in OpenBoardView or similar viewers. Before relying on any part locations or net names, make sure the SI variant and the PCB revision match the board on your bench.
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 @boardview. 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.