====== Aperture ======
An **aperture** or **window** is a small opening in a [[dial]], [[face]], or [[case]].

The most common aperture is the [[date window]] used to display the [[date]], often at 3 00 on the [[dial]]. Apertures are also used for other [[calendar]] functions, including [[day]], [[month]], [[year]], and so on on [[perpetual calendar]] watches. They can be used for [[GMT]] functions, [[rising hour]]s, and other [[complication]]s. Apertures can even reveal the [[movement]] through the [[face]] or [[case]] as in the case of [[open heart]] or [[skeleton]] designs.


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