diff --git a/io/src/main/java/org/gcube/resourcemanagement/manager/exception/RMException.java b/io/src/main/java/org/gcube/resourcemanagement/manager/exception/CodeException.java
similarity index 76%
rename from io/src/main/java/org/gcube/resourcemanagement/manager/exception/RMException.java
rename to io/src/main/java/org/gcube/resourcemanagement/manager/exception/CodeException.java
index 466f9ad..4adcca3 100644
--- a/io/src/main/java/org/gcube/resourcemanagement/manager/exception/RMException.java
+++ b/io/src/main/java/org/gcube/resourcemanagement/manager/exception/CodeException.java
@@ -6,15 +6,16 @@ package org.gcube.resourcemanagement.manager.exception;
  * @author Manuele Simi (ISTI CNR)
  *
  */
-public class RMException extends Exception {
+public class CodeException extends Exception {
 
 	private static final long serialVersionUID = 333945715086602250L;
 
 	private final int errorCode;
 	private final String errorMsg;
 
-	public RMException(ExceptionCode code) {
-		this.errorMsg = code.getMsg();
+	public CodeException(RMCode code) {
+		super();
+		this.errorMsg = code.getMessage();
 		this.errorCode = code.getId();
 	}
 
diff --git a/io/src/main/java/org/gcube/resourcemanagement/manager/exception/ErrorCode.java b/io/src/main/java/org/gcube/resourcemanagement/manager/exception/ErrorCode.java
index 58398d5..88f64ca 100644
--- a/io/src/main/java/org/gcube/resourcemanagement/manager/exception/ErrorCode.java
+++ b/io/src/main/java/org/gcube/resourcemanagement/manager/exception/ErrorCode.java
@@ -1,6 +1,3 @@
-/**
- * 
- */
 package org.gcube.resourcemanagement.manager.exception;
 
 /**
@@ -10,7 +7,15 @@ package org.gcube.resourcemanagement.manager.exception;
  *
  */
 public interface ErrorCode {
+	
+	/**
+	 * Identifier of the code.
+	 */
 	public int getId();
 
-	public String getMsg();
+	/**
+	 * The message associated to the code
+	 * @return the message
+	 */
+	public String getMessage();
 }
diff --git a/io/src/main/java/org/gcube/resourcemanagement/manager/exception/ExceptionCode.java b/io/src/main/java/org/gcube/resourcemanagement/manager/exception/ExceptionCode.java
deleted file mode 100644
index ce28bd9..0000000
--- a/io/src/main/java/org/gcube/resourcemanagement/manager/exception/ExceptionCode.java
+++ /dev/null
@@ -1,31 +0,0 @@
-package org.gcube.resourcemanagement.manager.exception;
-
-/**
- * Exception codes handled with {@link RMException}.
- * 
- * @author Manuele Simi (ISTI CNR)
- *
- */
-public enum ExceptionCode implements ErrorCode {
-	
-	INVALID_REQUEST(0, "The request is invalid"),
-	MISSING_PARAMETER(1, "Required query parameter is missing"),
-	MISSING_HEADER(2, "Required header is missing"),
-	CONTEXT_ALREADY_EXIST(3, "Required header is missing");
-	
-	private final int id;
-	private final String msg;
-
-	ExceptionCode(int id, String msg) {
-		this.id = id;
-		this.msg = msg;
-	}
-
-	public int getId() {
-		return this.id;
-	}
-
-	public String getMsg() {
-		return this.msg;
-	}
-}
diff --git a/io/src/main/java/org/gcube/resourcemanagement/manager/exception/RMCode.java b/io/src/main/java/org/gcube/resourcemanagement/manager/exception/RMCode.java
new file mode 100644
index 0000000..8026df6
--- /dev/null
+++ b/io/src/main/java/org/gcube/resourcemanagement/manager/exception/RMCode.java
@@ -0,0 +1,42 @@
+package org.gcube.resourcemanagement.manager.exception;
+
+import java.util.Arrays;
+
+/**
+ * Exception codes handled with {@link CodeException}.
+ * 
+ * @author Manuele Simi (ISTI CNR)
+ *
+ */
+public enum RMCode implements ErrorCode {
+
+	INVALID_REQUEST(0, "The request is invalid"), 
+	MISSING_PARAMETER(1,"Required query parameter is missing"), 
+	MISSING_HEADER(2, "Required header is missing"), 
+	CONTEXT_ALREADY_EXIST(3, "Required header is missing"),
+	INVALID_REQUEST_FOR_RR(4, "Failed to validate the request. The request was not submitted to the Resource Registry."),
+	GENERIC_ERROR_FROM_RR(5, "The Resource Registry returned an error.");
+
+
+	private final int id;
+	private final String msg;
+
+	RMCode(int id, String msg) {
+		if (exists(id))
+			throw new IllegalArgumentException(String.format("Code %d already exists", id));
+		this.id = id;
+		this.msg = msg;
+	}
+
+	public int getId() {
+		return this.id;
+	}
+
+	public String getMessage() {
+		return this.msg;
+	}
+	
+	protected static boolean exists(int id) {
+		return Arrays.stream(RMCode.values()).filter(v -> v.id == id).count() > 0;
+	}
+}