From the Momoyama period to the mid-Edo period, carved transoms became an essential part of Japanese-style home building (and decoration) because they played a crucial role in both ventilation and lighting. Transoms also allowed the scent of incense being burned in one room to reach other rooms. Transoms may be installed between the ceiling and the lintel in a house, between the interior and exterior, or between inner rooms and hallways. They may be carved differently depending on whether the core objective is to improve lighting or to increase air flow.