Archive linked to the Lenovo ThinkPad Edge E420 notebook, without a board number, revision or content type in the name. Edge series boards were often built by ODMs, so the PCB may carry a separate maker code worth checking. The package likely holds a schematic or boardview used to trace rails, inspect the power-on sequence and locate components near a short. Extract it to see what is inside, and match the board code printed on your motherboard with the document before relying on 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.