Compressed archive, 1.76 MB in RAR format, associated with Apple logic board 820-2733. No revision, Mac model or list of documents appears in the name. Apple uses the 820 prefix for its logic board part numbers, printed directly on the board, and confirming that number is essential before trusting schematic values. Use the contents, typically a schematic and perhaps boardview data, to follow power rails, check signal lines and locate components or test points during diagnosis.
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.