A schematic diagram for Apple hardware (board 820-3115). Shared as “Apple MacBook Pro - A1278 - J30 - 820-3115 3.pdf” — a .pdf file, 45.1 KB.
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 @ShareMan_Electronic_Files. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.