E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
E06B—FIXED OR MOVABLE CLOSURES FOR OPENINGS IN BUILDINGS, VEHICLES, FENCES OR LIKE ENCLOSURES IN GENERAL, e.g. DOORS, WINDOWS, BLINDS, GATES
E06B3/00—Window sashes, door leaves, or like elements for closing wall or like openings; Layout of fixed or moving closures, e.g. windows in wall or like openings; Features of rigidly-mounted outer frames relating to the mounting of wing frames
E06B3/70—Door leaves
E06B3/7003—Door leaves consisting of several adjacent similar elements, e.g. planks, without outer covering panels
Lozenge-shaped building panel - has ridges parallel to central channel with turned down extensions at ends joined to stepped panel side edges (SW 5.7.76)