A schematic diagram for Apple hardware (board 820-2936). Shared as “A1278 820-2936-B k90i PDF.rar” — a .rar file, 2.61 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 @alischematics. 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)