A boardview (component placement) file. Shared as “M57-DVT-MLB.bv” — a .bv file, 1.07 MB.
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 @ShareMan_Electronic_Files. Enginerys does not host this file.
How to open a .bv file
Older ATE boardview format, usually found for legacy laptop and desktop boards.
OpenBoardViewBoardViewer