On a battened gate the vertical battens can be spaced wide enough that someone reaches a hand through the front face and undoes the lock from the street side. The lock surround plate fixes that. It is a flat plate welded flush to the front face of the frame, sitting in the same plane as the battens, directly around the lockbox on the latch side.
The battens that would cross the plate are cut short and welded to its top and bottom edges, so there is no reach-through gap left around the lock. Typical plates run 150 to 250 mm wide and tall, a touch larger than the lockbox they cover, in 6 to 10 mm plate. The plate is welded on after the battens are tacked, then dressed flush.
CAD60 ties the surround plate to the lockbox option on the battened and patterned-battened pedestrian gates. You set its width, height, and depth (thickness); it inherits the lockbox height and hugs the latch edge. The crossing battens are cut to butt the plate on the front elevation, and the plate carries its own size callouts.