An Identity Mapping nonlocal coupling () maps between geometric entities that overlap, possibly when viewed in different frames. When it is evaluated at a specific set of coordinates in the destination frame, its argument is evaluated with the same coordinates in the source frame. The default Operator name is idmap1.

Select a Source frame to use on the source geometric entity and a Destination frame to use on the destination geometric entity. In most cases the default Spatial frame can be used since that will create a mapping between the points which coincide at each instant when the geometry is deforming. In other cases, the Material, Geometry, or Mesh frame can be more appropriate, but typically the same frame is used for both source and destination.