All the Profile define bundling as only aggregation option. ( see the MH-admit profile in the link as an examlpe) This precludes contained resources. Some implementers may need to contain certain resources like fo example, Coverage, since they are not separate in there systems. Should add option of contained to all or some of the references. Along with discussion to follow the guidance in the FHIR speicificaiton on when to use contained resources. Need to clarify whether and how the GraphDefinition can indicate if contained allowed or not.