What is (a) A return in one of the corners of the architrave of a door or window; -- called also ancon, ear, elbow. (b) The shoulder of a joggled keystone called?

crossette — (a) A return in one of the corners of the architrave of a door or window; -- called also ancon, ear, elbow. (b) The shoulder of a joggled keystone. (Webster's 1913.)

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