Boardview for the Apple iPad 3 logic board, stored as a .pcb file of about 21.2 MB; the (2) suffix suggests a second copy or variant of the same file, and another iPad 3 view exists with a (1) suffix. Comparing both may help if one fails to open. The view shows component positions, designators and net connectivity for locating shorts, test points and connectors. Open it with a compatible boardview viewer, and confirm the board in hand is an iPad 3 before trusting any location.
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 @boardview. 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.