Boardview for the Lenovo ThinkPad X250 mainboard NM-A091, packed in a 1.14 MB RAR. NM-prefixed numbers come from LCFC, the Lenovo-Compal joint venture that designs many ThinkPad boards. A boardview shows component placement, part names and net connections on both sides of the PCB, letting you locate test points, follow a rail or find which part shorts it. Open it with OpenBoardView, FlexBV or a similar viewer, and confirm NM-A091 on the board silkscreen before measuring against 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 @hrtechno. 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.