Boardview for Apple logic board 820-00165, the companion to the schematic of the same number. The 525 KB .brd file opens in viewers such as OpenBoardView or FlexBV and shows component placement, net connections and pin locations on both sides of the board. It is used to find test points, measure rails to ground, and locate the exact capacitor or IC named in the schematic. Confirm the 820 number printed on your board matches before probing or removing parts.
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 @ITHINKHS. Enginerys does not host this file.
How to open a .brd file
The most common boardview extension. Several unrelated formats share it, which is why one viewer opens a .brd and another refuses it.