Boardview for the MSI MS-7C50 motherboard, revision 1.0, packed in a ZIP archive of 987 KB with the layout in CAD format. The name marks it as BDV, meaning boardview data rather than a schematic. Technicians open such files in a viewer like OpenBoardView, FlexBV or a similar CAD-reading tool to find parts by reference designator, follow nets between pins and locate test points when chasing a short or a dead rail. MS-numbers are MSI's own internal board codes, so read the number and revision silkscreened on the PCB before trusting the coordinates.
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 @cyberlanelectonik. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.