diff --git a/src/org/gcube/application/framework/core/util/SessionConstants.java b/src/org/gcube/application/framework/core/util/SessionConstants.java
index 02f1ec0..e609a7a 100644
--- a/src/org/gcube/application/framework/core/util/SessionConstants.java
+++ b/src/org/gcube/application/framework/core/util/SessionConstants.java
@@ -127,4 +127,9 @@ public class SessionConstants {
 	 * the id of the active query to be presented
 	 */
 	public static final String activePresentationQueryNo = "activePresentationQueryNo";
+	
+	/**
+	 * the collections hierarchy (groups - collections)
+	 */
+	public static final String collectionsHierarchy = "collectionsHierarchy";
 }