A boardview (component placement) file for Apple hardware (board 820-3482). Shared as “iMAC A1418 - 820-3482-A.rar” — a .rar file, 8.26 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 @Laptopbiossolutions. 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)