diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/ElementManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/ElementManagement.java
index e3410d1..a3551f5 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/ElementManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/ElementManagement.java
@@ -73,6 +73,10 @@ public abstract class ElementManagement<El extends OElement, T extends Type> {
 	public final static String AT = "@";
 	public final static String UNDERSCORE = "_";
 	
+	public final static String IN_PREFIX = "in_";
+	public final static String OUT_PREFIX = "out_";
+	
+	
 	/* *
 	 * The classes which has not to be included in the superClasses property when serialize and instance
 	 * e.g. for any Resource instance when mast not include Entity and any Entity super class 
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/entities/EntityElementManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/entities/EntityElementManagement.java
index 2c51c6d..3cd095b 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/entities/EntityElementManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/entities/EntityElementManagement.java
@@ -43,10 +43,10 @@ public abstract class EntityElementManagement<E extends EntityElement, ET extend
 		
 		this.ignoreKeys.add(EntityElement.HEADER_PROPERTY);
 		
-		this.ignoreStartWithKeys.add(com.tinkerpop.blueprints.impls.orient.OrientVertex.CONNECTION_IN_PREFIX.toLowerCase());
-		this.ignoreStartWithKeys.add(com.tinkerpop.blueprints.impls.orient.OrientVertex.CONNECTION_OUT_PREFIX.toLowerCase());
-		this.ignoreStartWithKeys.add(com.tinkerpop.blueprints.impls.orient.OrientVertex.CONNECTION_IN_PREFIX.toUpperCase());
-		this.ignoreStartWithKeys.add(com.tinkerpop.blueprints.impls.orient.OrientVertex.CONNECTION_OUT_PREFIX.toUpperCase());
+		this.ignoreStartWithKeys.add(IN_PREFIX.toLowerCase());
+		this.ignoreStartWithKeys.add(OUT_PREFIX.toLowerCase());
+		this.ignoreStartWithKeys.add(IN_PREFIX.toUpperCase());
+		this.ignoreStartWithKeys.add(OUT_PREFIX.toUpperCase());
 		
 		this.relationManagements = new HashMap<>();
 		
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/model/entities/EntityManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/model/entities/EntityManagement.java
index cff239c..8a9b0a6 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/model/entities/EntityManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/model/entities/EntityManagement.java
@@ -133,10 +133,10 @@ public abstract class EntityManagement<E extends Entity, ET extends EntityType>
 		
 		this.ignoreKeys.add(Entity.HEADER_PROPERTY);
 		
-		this.ignoreStartWithKeys.add(com.tinkerpop.blueprints.impls.orient.OrientVertex.CONNECTION_IN_PREFIX.toLowerCase());
-		this.ignoreStartWithKeys.add(com.tinkerpop.blueprints.impls.orient.OrientVertex.CONNECTION_OUT_PREFIX.toLowerCase());
-		this.ignoreStartWithKeys.add(com.tinkerpop.blueprints.impls.orient.OrientVertex.CONNECTION_IN_PREFIX.toUpperCase());
-		this.ignoreStartWithKeys.add(com.tinkerpop.blueprints.impls.orient.OrientVertex.CONNECTION_OUT_PREFIX.toUpperCase());
+		this.ignoreStartWithKeys.add(IN_PREFIX.toLowerCase());
+		this.ignoreStartWithKeys.add(OUT_PREFIX.toLowerCase());
+		this.ignoreStartWithKeys.add(IN_PREFIX.toUpperCase());
+		this.ignoreStartWithKeys.add(OUT_PREFIX.toUpperCase());
 		
 		this.relationManagements = new HashMap<>();