I haven't seen it described as "ornamental painting" on COA, but what I suspect it's referring to is the exterior window trim pieces. On ROW/Euro 930s these were black (I believe powdercoated or anodized actually rather than paint), on US 930s they were typically chrome. I think US you could have black as an option.
First picture pictures is my '77 930 which was originally a German market car which has the black trim. Second picture shows the chrome trim on another car.
