<> <> <> <> DIRECTORY CD; CDDefaultsExtras: CEDAR DEFINITIONS = BEGIN PureLayer: PROC [layer: CD.Layer] RETURNS [CD.Layer]; <<--returns corresponding real layer>> <<--usage: given layer as control panel value, this returns mask layer to be used>> <<--for cases which do not accept abstract layers>> Substitute: PRIVATE PROC [abstract: CD.Layer, pure: CD.Layer]; <<--only technology implementor should call this procedure>> END.