Boardview for a Lenovo mainboard NM-A251, with NM-A252 also referenced; the BOT tag suggests a bottom-side layer view. The NM-xxxx pattern is used by LCFC, Lenovo's own design unit, for many IdeaPad and ThinkPad boards. A boardview lets technicians find component locations, nets and test points, follow power rails and narrow down shorts on the underside of the PCB. Open it in OpenBoardView, FlexBV or a similar viewer after extracting, and confirm the NM number silkscreened on the board matches.
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 @cynetitsolution. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.