diff --git a/src/main/java/org/gcube/informationsystem/discovery/ClassElementInformation.java b/src/main/java/org/gcube/informationsystem/discovery/ClassInformation.java
similarity index 82%
rename from src/main/java/org/gcube/informationsystem/discovery/ClassElementInformation.java
rename to src/main/java/org/gcube/informationsystem/discovery/ClassInformation.java
index 36bd29f..311c3de 100644
--- a/src/main/java/org/gcube/informationsystem/discovery/ClassElementInformation.java
+++ b/src/main/java/org/gcube/informationsystem/discovery/ClassInformation.java
@@ -4,10 +4,13 @@ import java.util.LinkedHashSet;
 import java.util.Set;
 
 import org.gcube.informationsystem.base.reference.Element;
-import org.gcube.informationsystem.tree.NodeElementInformation;
+import org.gcube.informationsystem.tree.NodeInformation;
 import org.gcube.informationsystem.types.TypeMapper;
 
-public class ClassElementInformation implements NodeElementInformation<Class<Element>> {
+/**
+ * @author Luca Frosini (ISTI - CNR)
+ */
+public class ClassInformation implements NodeInformation<Class<Element>> {
 
 	@Override
 	public String getIdentifier(Class<Element> clz) {
diff --git a/src/main/java/org/gcube/informationsystem/tree/Node.java b/src/main/java/org/gcube/informationsystem/tree/Node.java
index e2c52b4..29da37c 100644
--- a/src/main/java/org/gcube/informationsystem/tree/Node.java
+++ b/src/main/java/org/gcube/informationsystem/tree/Node.java
@@ -71,7 +71,7 @@ public class Node<T> implements Comparable<Node<T>> {
 		for (int i = 0; i < level; ++i) {
 			stringBuffer.append(Node.INDENTATION);
 		}
-		stringBuffer.append(tree.getNodeElementInformation().getIdentifier(t));
+		stringBuffer.append(tree.getNodeInformation().getIdentifier(t));
 		for (Node<T> child : children) {
 			stringBuffer.append("\n");
 			stringBuffer.append(child.createTree(level+1));
@@ -91,9 +91,9 @@ public class Node<T> implements Comparable<Node<T>> {
 			return -1;
 		}
 		
-		NodeElementInformation<T> nei = tree.getNodeElementInformation();
+		NodeInformation<T> ni = tree.getNodeInformation();
 		
-		return nei.getIdentifier(t).compareTo(nei.getIdentifier(other.t));
+		return ni.getIdentifier(t).compareTo(ni.getIdentifier(other.t));
 	}
 	
 	
diff --git a/src/main/java/org/gcube/informationsystem/tree/NodeElementInformation.java b/src/main/java/org/gcube/informationsystem/tree/NodeInformation.java
similarity index 92%
rename from src/main/java/org/gcube/informationsystem/tree/NodeElementInformation.java
rename to src/main/java/org/gcube/informationsystem/tree/NodeInformation.java
index b50457b..0ddbe21 100644
--- a/src/main/java/org/gcube/informationsystem/tree/NodeElementInformation.java
+++ b/src/main/java/org/gcube/informationsystem/tree/NodeInformation.java
@@ -2,7 +2,7 @@ package org.gcube.informationsystem.tree;
 
 import java.util.Set;
 
-public interface NodeElementInformation<T> {
+public interface NodeInformation<T> {
 
 	public abstract String getIdentifier(T t);
 	
diff --git a/src/main/java/org/gcube/informationsystem/tree/Tree.java b/src/main/java/org/gcube/informationsystem/tree/Tree.java
index d0a20ee..f5d1db0 100644
--- a/src/main/java/org/gcube/informationsystem/tree/Tree.java
+++ b/src/main/java/org/gcube/informationsystem/tree/Tree.java
@@ -12,12 +12,12 @@ public class Tree<T> {
 	private boolean allowMultipleInheritance;
 	
 	private Node<T> root;
-	private NodeElementInformation<T> nei;
+	private NodeInformation<T> ni;
 	private Map<String, Node<T>> locate;
 	
-	public Tree(T t, NodeElementInformation<T> nei) throws Exception {
-		this.allowMultipleInheritance = false;
-		this.nei = nei;
+	public Tree(T t, NodeInformation<T> ni) throws Exception {
+		this.allowMultipleInheritance = true;
+		this.ni = ni;
 		this.locate = new HashMap<>();
 		this.root = addNode(t);
 		
@@ -27,20 +27,20 @@ public class Tree<T> {
 		this.allowMultipleInheritance = allowMultipleInheritance;
 	}
 	
-	public NodeElementInformation<T> getNodeElementInformation() {
-		return nei;
+	public NodeInformation<T> getNodeInformation() {
+		return ni;
 	}
 	
 	public Node<T> addNode(T t) {
-		String identifier = nei.getIdentifier(t);
+		String identifier = ni.getIdentifier(t);
 		if(locate.containsKey(identifier)) {
-			// Has been already added
+			// has been already added
 			return locate.get(identifier);
 		}
 		
 		Node<T> node = new Node<>(t);
 		
-		Set<String> parentIdentifiers = nei.getParentIdentifiers(root.getNodeElement(), t);
+		Set<String> parentIdentifiers = ni.getParentIdentifiers(root.getNodeElement(), t);
 		for(String parentIdentifier : parentIdentifiers) {
 			Node<T> parentNode = locate.get(parentIdentifier);
 			if(parentNode==null) {
@@ -55,7 +55,7 @@ public class Tree<T> {
 		}
 		
 		this.locate.put(identifier, node);
-		this.nei.extraElaboration(t);
+		this.ni.extraElaboration(t);
 		
 		return node;
 	}