If a collection does not allow duplicate keys and the startAtObject method is called with an object that is not in the collection but the object has the same keys as an object that is in the collection, the iterator will be positioned to return the object with that key in the collection when either the next or back method is called. If the next method is called, the object will be returned even if the instance identifier is less than the instance identifier of the startAtObject method object parameter value. If the back method is called, the object will be returned even if the instance identifier is greater than the instance identifier of the startAtObject method object parameter value.

If a collection allows duplicate keys and the startAtObject method is called with an object that is not in the collection but the object has the same keys as one or more objects that are in the collection, the instance identifier of the object passed to the startAtObject method is taken into account when positioning the iterator. Only the objects in the collection with an instance identifier greater than the object identifier of the startAtObject method will be returned for the next method and less than the object identifier of the startAtObject method for the back method.