Boardview for the Apple MacBook Pro 13-inch A1278 with logic board 820-3115-A, supplied in a small RAR archive. The BDV format opens in boardview readers such as OpenBoardView or FlexBV. Apple 820-xxxx numbers identify the logic board, and the suffix marks its revision. Use the view to locate components, measure test points, follow nets such as PP3V42_G3H or PPBUS_G3H and find shorted parts. Confirm the 820 number on your board, as A1278 units used several different logic boards over the years.
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 @pkbiosbdv. 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.