Boardview for a Lenovo desktop board identified as I4X0MS version 1.0, compressed into a 1.97 MB RAR archive. The name gives no specific PC model, only this board code and revision. After extraction it opens in a viewer such as OpenBoardView, FlexBV or Boardviewer, mapping component positions, nets and pins so a technician can follow power rails, find test points and isolate shorts. Check that the code and version silkscreened on the motherboard match before using it for diagnosis.
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 @BoardSchematic. 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.