Archive for Apple logic board 820-2023, with no schematic number or revision given in the name. At 1.59 MB it most plausibly contains a full schematic, which helps with following rails, checking signal routing and identifying components during diagnosis. Because the revision is not stated, compare the pages against the physical board, especially part values and optional component placements. The 820 prefix is Apple's own PCB numbering and appears on the board silkscreen. Open it with WinRAR or 7-Zip before use.
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 @Mac_Shematic_Santale. 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.