A boardview (component placement) file for Apple hardware (board 820-01521). Shared as “820-01521 PJJ MLB Pre-EVT2 BOARDVIEW(BDV)(.BRD) .rar” — a .rar file, 94.2 KB.
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 @generalbios. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.
7-ZipWinRARThe Unarchiver (macOS)