Flanking window A framed margin light, side light, or wing light is positioned on either side of the door or window. Windows Terms Texts From Articles (1) Part 2: Apertures for View Apertures have many purposes of uses. They are used as light sources, as ventilation, and as portals through which people pass. In each of these examples, they are opened to allow some physical thing … Nahoko Wada (Architectural Historian) 18 Oct 2017