Yeah, I finally figured out that the holes could be for lights; after I made overhead provision for Hella dome lights (glued in 12mm okoume discs with grooves routed for wires). They look like stretched out pierced ears to me. I can say that they have nothing to do with the hinges, though they certainly strengthen the shell at the upper door hinge – a very good thing if someone hangs on the door. I can say that CLC’s lights are mounted on the bulkhead, not in the door sill.