Small RAR archive of 429 KB for the Apple logic board 820-4652. The name does not reveal whether it holds a schematic, a boardview or both, and no revision letter is given. Apple uses 820-xxxx part numbers for its own logic boards, with a suffix letter marking the revision. Match the full number silkscreened on the board before using the files. Boardview contents open in tools like OpenBoardView or FlexBV, which help locate components, test points and net connections during repair.
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 .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.