Archive for Apple logic board 820-00244, stored as a 1.55 MB RAR file; the name does not state the Mac model or the type of contents. Apple uses the 820-xxxxx pattern for its logic board part numbers, printed directly on the PCB, so match that number before using anything inside. Depending on the contents, it may be a firmware dump for the SPI flash or board documentation for tracing circuits. If it is firmware, read and save the original chip before writing, and check that the image size matches the flash chip.
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 @schematicslaptop. 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.