diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/AccessPath.java b/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/AccessPath.java
index 711f1bb..493a87c 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/AccessPath.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/AccessPath.java
@@ -34,10 +34,10 @@ public class AccessPath {
 	public static final String RELATION_TYPE_PATH_PART = "RELATION_TYPE_NAME";
 	public static final String REFERENCE_TYPE_PATH_PART = "REFERENCE_TYPE_NAME";
 	
-	public static final String REFERENCE_PARAM = "reference";
-	public static final String POLYMORPHIC_PARAM = "polymorphic";
-	public static final String DIRECTION_PARAM = "direction";
-	public static final String INCLUDE_RELATION_PARAM = "includeRelation";
+	public static final String _REFERENCE_PARAM = "_reference";
+	public static final String _POLYMORPHIC_PARAM = "_polymorphic";
+	public static final String _DIRECTION_PARAM = "_direction";
+	public static final String _INCLUDE_RELATION_PARAM = "_includeRelation";
 	
 	public static final String CURRENT_CONTEXT = "CURRENT_CONTEXT";
 	
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/InstancePath.java b/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/InstancePath.java
index 705fe22..76f122e 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/InstancePath.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/InstancePath.java
@@ -4,7 +4,7 @@ public class InstancePath {
 	
 	public static final String INSTANCES_PATH_PART = "instances";
 	
-	public static final String POLYMORPHIC_PARAM = AccessPath.POLYMORPHIC_PARAM;
+	public static final String POLYMORPHIC_PARAM = "polymorphic";
 	
 	public static final String HIERARCHICAL_MODE_PARAM = "hierarchical";
 	
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/TypePath.java b/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/TypePath.java
index 21c4f42..c777863 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/TypePath.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/TypePath.java
@@ -7,6 +7,6 @@ public class TypePath {
 	
 	public static final String TYPES_PATH_PART = "types";
 	
-	public static final String POLYMORPHIC_PARAM = AccessPath.POLYMORPHIC_PARAM;
+	public static final String POLYMORPHIC_PARAM = "polymorphic";
 	
 }
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