Boardview file for the MSI MS-7557 motherboard, version 20 according to the name, saved in the .cad format. Unlike a schematic, a boardview shows the physical placement of every part, pin and net, so you can click a net and see all connected pads and test points. The .cad format is commonly opened with boardview viewers such as FlexBV, OpenBoardView or similar tools. Use it together with the schematic to locate a component quickly, probe a rail or find what is shorted to ground. Confirm the PCB revision matches before trusting placement.
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 @pepeelectronica. 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.