public List<IDifference> getDifferences() {
List<IDifference> results = new ArrayList<IDifference>();
IMetaRepresentation rep = MetaRepresentation.getInstance();
IModel am = rep.getAmModel();
IModel dm = rep.getDmModel();
List<IModelItem> amItems = am.getItems();
List<IModelItem> dmItems = dm.getItems();
// entering the comparision
for (IModelItem amItem : amItems) {
String amID = amItem.getIdentifier();