A transom refers to a horizontal beam or bar that separates a door or window from additional panels or lights above it. In the context of doors, a transom is the horizontal bar dividing the door from a window above it. It can be a decorative element or a structural component supporting the window or panels above the door. Transoms above doors can be fixed or operable, allowing for ventilation or additional light into the space. For windows, a transom is a horizontal dividing bar between the main window section and smaller windows or panels situated above it. These additional window panels can be fixed or operable, providing extra light, ventilation, or a decorative touch to the window design.