Apple logic board 820-00239 package, a 6.15 MB zip whose name states only the board number. The Mac model, revision and contents are not given, so inspect the archive first. It likely contains a schematic and possibly a boardview or firmware. The newer five-digit 820 numbering identifies the specific logic board. Use the files to trace rails, find test points and diagnose shorts. If a ROM dump is included, back up the existing chip first and check that the image size matches the flash part.
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 @notebookschematic. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.