US Patent 6860064 Selectively positionable covering arrangement

A selectively positionable covering arrangement comprises a slotted track member mounted to a vertical wall and extending across the top of an opening in the wall, at least first and second cover members one of which is mounted to the track and relatively laterally slidable between a first position wherein the cover members are coplanar with one another and in parallel juxtaposed covering relation with a respective first and second closure members of the opening and into a second position wherein the cover members are in spaced parallel juxtaposed relation with one another and juxtaposed with one of the closure members whereby to uncover the other of the closure members.