DIFF Subgroup
E04D 13/0305 Full Title
Special arrangements or devices in connection with roof coverings; Roof drainage (ventilation tiles E04D1/30; ventilation slabs E04D3/40; internal channels E04F17/00) > Sky-lights; Domes; Ventilating sky-lights (E04D13/14 takes precedence; structures therefor, E04B7/18; )
Of 2 combined children, 0 exist in both systems.
2 codes are CPC-only extensions.