Height. The overall height of the skylight window opening.

Width. The overall width of the skylight window opening.

Frame Depth. The depth of the window frame.

Frame Width. The thickness of the window frame.

Frame Offset. The offset of the window frame from the roof surface.

Sash Offset. The distance the sash sits back in the window frame. The sash is the frame that holds the glass.

Sash Depth. The thickness of the sash in plan view.

Sash Width. The width of the sash in elevation.