Boardview in CAD format for a Quanta board identified only as X8M, about 2.26 MB. The name does not give the laptop brand or a full DA board number, so match the X8M code against the label on the PCB. CAD boardviews open in OpenBoardView, FlexBV and similar viewers, which show part locations, net connections and test points. Technicians use this to trace rails, find a shorted component, and probe signals without a microscope search of the whole board.
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 @notebookschematic. Enginerys does not host this file.
How to open a .cad file
GenCAD text export, the usual format for Compal, Quanta, Wistron and Dell / HP / Lenovo laptop boards.