Apple logic board package for 820-3787 at revision A, packed as a 4.01 MB RAR file. The name does not list the contents, but a size like this often means a schematic PDF, possibly together with a boardview. Apple prints the 820 number and revision letter on the PCB, so check both before trusting rail names or part locations. With the schematic and boardview side by side, a technician can follow power rails, measure test points and isolate shorted components efficiently.
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.