RAR archive for LX3 and LX5 boards based on the Intel Huron River platform, the Sandy Bridge era mobile platform with HM6x chipsets. The name lists no brand or exact board number, so the document inside should be checked to confirm which model it covers. Expect a schematic used to trace power rails, follow the CPU and PCH power sequence and locate test points. Compare the board identification printed on the PCB with the title block before using it for measurements or part replacement.
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 @generalschematics. 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.