The CAP is where drilling is the style most rectangle. Some framed Some do not have a frame. Some has opened. Some don't have Windows handy to provide airflow.
The area is a rectangle that is drilled to cap greenhouse majority. Some of the frame Some of frameless Some houses have no windows open somewhere handy to have air circulation.
Is the drill before the rectangle frame is mainly. Some are some of no frame, some are bloom turned off. Some there. The window is useful to the circulation of air.