RAR archive of 685 KB tagged Dell XM2; the name is cryptic and gives no model, board number or document type, so XM2 cannot be expanded with certainty. Extract it and check the title block to identify the exact device and board. At this size a schematic PDF is the probable content, used for tracing rails, locating components and diagnosing shorts or no-power faults. Only rely on it after confirming the board number and revision printed on the PCB match the document.
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.