A boardview (component placement) file for Apple hardware (board 820-00281, 820-00928). Shared as “J80_MLB 820-00281 820-00928-04 For reference.pcb” — a .pcb file, 2.66 MB.
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 .pcb file
In repair archives a .pcb is typically an XZZ (XinZhiZao) boardview — popular for phones and recent laptops.
XZZ PCB viewerOpenBoardView (recent builds)FlexBV