Boardview file for the ASUS G531GW gaming laptop mainboard in CAD format, where the number 16 in the name likely marks a revision or file version. ASUS CAD boardviews open in tools such as OpenBoardView, FlexBV or Boardviewer. They show component placement, net names and pin connections on both sides of the PCB. Use it to locate test points, follow power rails and check suspected shorts. Compare the board revision printed on the PCB before relying on part positions.
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.