Upper Flap Skin Trimming/Bending?

On drawing 15 there is a "detail D" that shows part of the upper flap skin being altered. I'm afraid I don't quite understand what it is showing. Any help out there??

Could it be where the flap top skin meets the fuselage? Then the bottom skin should be close to touching the fuselage. Or is it where the flap skin hits on the flap brace on the rear spar when the flaps are up? A small section has to be trimmed and rebent so the flap can go up all the way. At least that's how it was done on the RV-6. I don't have my old RV-4 plans set with me to look at right now.