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 4d9f0be..f5c391b 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
@@ -16,10 +16,20 @@ public class AccessPath {
 	
 	public static final int DEFAULT_LIMIT = 20;
 	
-	public static final String FACET_PATH_PART = "facet";
-	public static final String RESOURCE_PATH_PART = "resource";
+	public static final String FACET_PATH_PART = ERPath.FACET_PATH_PART;
+	public static final String RESOURCE_PATH_PART = ERPath.RESOURCE_PATH_PART;
 	
-	public static final String SCHEMA_PATH_PART = "schema";
+	public static final String EMBEDDED_PATH_PART = ERPath.EMBEDDED_PATH_PART;
+	
+	public static final String CONSISTS_OF_PATH_PART = ERPath.CONSISTS_OF_PATH_PART;
+	public static final String IS_RELATED_TO_PATH_PART = ERPath.IS_RELATED_TO_PATH_PART;
+	
+	public static final String SCHEMA_PATH_PART = SchemaPath.SCHEMA_PATH_PART;
 	public static final String INSTANCE_PATH_PART = "instance";
 	
+	public static final String INCLUDE_SUBTYPES_PARAM = "includeSubtypes";
+	public static final String INCLUDE_SCHEMA_PARAM = "includeSchema";
+	
+	public static final String POLYMORPHIC_PARAM = "polymorphic";
+	
 }
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/EntityPath.java b/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/ERPath.java
similarity index 69%
rename from src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/EntityPath.java
rename to src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/ERPath.java
index fcdcc1f..e65552e 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/EntityPath.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/ERPath.java
@@ -6,13 +6,19 @@ package org.gcube.informationsystem.resourceregistry.api.rest;
 /**
  * @author Luca Frosini (ISTI - CNR)
  */
-public class EntityPath {
+public class ERPath {
 	
-	public static final String ENTITY_PATH_PART = "entity";
+	public static final String ER_PATH_PART = "er";
+	
+	protected static final String EMBEDDED_PATH_PART = "embedded";
+	
+	protected static final String ENTITY_PATH_PART = "entity";
 	
 	public static final String FACET_PATH_PART = "facet";
 	public static final String RESOURCE_PATH_PART = "resource";
 	
+	protected static final String RELATION_PATH_PART = "relation";
+	
 	public static final String CONSISTS_OF_PATH_PART = "consistsOf";
 	public static final String IS_RELATED_TO_PATH_PART = "isRelatedTo";
 	
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/SchemaPath.java b/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/SchemaPath.java
index da99149..28c9798 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/SchemaPath.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/SchemaPath.java
@@ -10,11 +10,12 @@ public class SchemaPath {
 	
 	public static final String SCHEMA_PATH_PART = "schema";
 	
-	public static final String FACET_PATH_PART = "facet";
-	public static final String RESOURCE_PATH_PART = "resource";
+	public static final String FACET_PATH_PART = ERPath.FACET_PATH_PART;
+	public static final String RESOURCE_PATH_PART = ERPath.RESOURCE_PATH_PART;
 	
-	public static final String EMBEDDED_PATH_PART = "embedded";
+	public static final String EMBEDDED_PATH_PART = ERPath.EMBEDDED_PATH_PART;
+	
+	public static final String CONSISTS_OF_PATH_PART = ERPath.CONSISTS_OF_PATH_PART;
+	public static final String IS_RELATED_TO_PATH_PART = ERPath.IS_RELATED_TO_PATH_PART;
 	
-	public static final String CONSISTS_OF_PATH_PART = "consistsOf";
-	public static final String IS_RELATED_TO_PATH_PART = "isRelatedTo";
 }