diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/ERManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/ERManagement.java
index 26eea33..decec1e 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/ERManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/ERManagement.java
@@ -63,7 +63,7 @@ import com.tinkerpop.blueprints.util.StringFactory;
 /**
  * @author Luca Frosini (ISTI - CNR)
  */
-public abstract class ERManagement<ERType extends ER, El extends Element> {
+public abstract class ERManagement<El extends Element> {
 	
 	protected Logger logger = LoggerFactory.getLogger(this.getClass());
 	
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/entities/BaseEntityManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/entities/BaseEntityManagement.java
index bb72fc9..7ed4d6b 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/entities/BaseEntityManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/entities/BaseEntityManagement.java
@@ -28,7 +28,7 @@ import com.tinkerpop.blueprints.impls.orient.OrientVertex;
 /**
  * @author Luca Frosini (ISTI - CNR)
  */
-public abstract class BaseEntityManagement<E extends BaseEntity> extends ERManagement<E,Vertex> {
+public abstract class BaseEntityManagement<E extends BaseEntity> extends ERManagement<Vertex> {
 	
 	/**
 	 * Provide a cache edge-internal-id -> RelationManagement 
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/relations/BaseRelationManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/relations/BaseRelationManagement.java
index b144c09..f97b360 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/relations/BaseRelationManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/relations/BaseRelationManagement.java
@@ -27,7 +27,7 @@ import com.tinkerpop.blueprints.impls.orient.OrientGraph;
  * @author Luca Frosini (ISTI - CNR)
  */
 public abstract class BaseRelationManagement<R extends BaseRelation<S, T>, SEM extends BaseEntityManagement<S>, TEM extends BaseEntityManagement<T>, S extends BaseEntity, T extends BaseEntity>
-		extends ERManagement<R,Edge> {
+		extends ERManagement<Edge> {
 	
 	protected final Class<S> sourceEntityClass;
 	protected final Class<T> targetEntityClass;
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/type/SchemaManagementImpl.java b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/type/SchemaManagementImpl.java
index 0db41ad..5c5d744 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/type/SchemaManagementImpl.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/type/SchemaManagementImpl.java
@@ -140,8 +140,6 @@ public class SchemaManagementImpl implements SchemaManagement {
 	}
 	
 	protected static TypeDefinition getTypeDefinition(OClass oClass) throws SchemaException {
-		// TODO OrientSerilizatoin is not acceptable anymore since TypeDefiniton introduction  
-		
 		ODocument oDocument = ((OClassImpl) oClass).toStream();
 		String json = oDocument.toJSON();
 		try {
@@ -156,7 +154,6 @@ public class SchemaManagementImpl implements SchemaManagement {
 				node.put(ISManageable.CLASS_PROPERTY, RelationTypeDefinition.NAME);
 			} 
 			
-			
 			ArrayNode arrayNode = (ArrayNode) node.get(TypeDefinition.PROPERTIES_PROPERTY);
 			Iterator<JsonNode> iterator = arrayNode.iterator();
 			while(iterator.hasNext()) {
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/type/properties/PropertyTypeDefinitionManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/type/properties/PropertyTypeDefinitionManagement.java
new file mode 100644
index 0000000..7d3fb07
--- /dev/null
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/type/properties/PropertyTypeDefinitionManagement.java
@@ -0,0 +1,5 @@
+package org.gcube.informationsystem.resourceregistry.instances.type.properties;
+
+public class PropertyTypeDefinitionManagement {
+	
+}