Compressed RAR of 1.47 MB for the Apple 820-2223 board, with no revision, model or content details in the name. Open it with WinRAR or 7-Zip to see whether it holds a schematic PDF, a boardview or both. Before relying on it, check that the 820 number on the PCB matches and look for the revision letter. Schematics for Apple boards are mainly used to trace power rails, check the standby and main rails in order, and locate filter capacitors or chips causing a short.
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.