Glossary
A. Oculus: A small circular opening, and which was a precursor of the Gothic rose window.
B. Foil: Circular segments combined concentrically with other foils to form the tracery used in rose windows. The foil is usually used in groups such as trefoil or quatrefoil.
C. Tabernacle: a canopied niche holding a sculpted figure, such as the rendering of saints and angels on the façade and transept of Reims cathedral.