TopLevelReference is used to denote which items in the Fragment Instance are the specific results of a query or process. For example, if a user queries for a Variable, the response may include several items in the returned FragmentInstance: the Variable, several related Concepts, CodeLists, Questions, or other referenced items. In order to clarify which item is the main item in response to a query, a reference to that item can be specified as a TopLevelReference. Note that if a Identifiable object is being resolved, the query will be to the parent Versionable or Maintainable. TypeOfObject should be set to any Versionable or Maintainable object.