Many signs have metaphoric mappings as well as iconic or metonymic ones. For these signs there are three way correspondences between a form, a concrete source and an abstract target meaning. The ASL sign LEARN has this three way correspondence. The abstract target meaning is "learning". The concrete source is putting objects into the head from books. The form is a grasping hand moving from an open palm to the forehead. The iconic correspondence is between form and concrete source. The metaphorical correspondence is between concrete source and abstract target meaning. Because the concrete source is connected to two correspondences linguistics refer to metaphorical signs as "double mapped".