diff --git a/src/main/java/envoy/event/HandshakeRejection.java b/src/main/java/envoy/event/HandshakeRejection.java
index 7033373..3eeb1d9 100644
--- a/src/main/java/envoy/event/HandshakeRejection.java
+++ b/src/main/java/envoy/event/HandshakeRejection.java
@@ -2,8 +2,8 @@ package envoy.event;
 
 /**
  * Signifies to the client that the handshake failed for the attached
- * reason.<br>
- * <br>
+ * reason.
+ * <p>
  * Project: <strong>envoy-common</strong><br>
  * File: <strong>HandshakeRejection.java</strong><br>
  * Created: <strong>28 Jan 2020</strong><br>
@@ -14,23 +14,44 @@ package envoy.event;
 public class HandshakeRejection extends Event<String> {
 
 	/**
-	 * Select this value if a given password hash or user was incorrect.
+	 * Select this value if a given password hash or user name was incorrect.
+	 * 
+	 * @since Envoy Common v0.3-alpha
 	 */
 	public static final String WRONG_PASSWORD_OR_USER = "Incorrect user name or password.";
 
 	/**
-	 * Select this value if the handshake could not be completed for some reason.
+	 * Select this value if a given user name for a registration is already taken.
+	 * 
+	 * @since Envoy Common v0.1-beta
+	 */
+	public static final String USERNAME_TAKEN = "Incorrect user name or password.";
+
+	/**
+	 * Select this value if the version of the client is incompatible with the
+	 * server.
+	 * 
+	 * @since Envoy Common v0.1-beta
+	 */
+	public static final String WRONG_VERSION = "Incompatible client version";
+
+	/**
+	 * Select this value if the handshake could not be completed for some different
+	 * reason.
+	 * 
+	 * @since Envoy Common v0.3-alpha
 	 */
 	public static final String INTERNAL_ERROR = "An internal error occured.";
 
 	private static final long serialVersionUID = 0L;
 
 	/**
-	 * Creates an instance of {@link HandshakeRejection} with an empty reason.
+	 * Creates an instance of {@link HandshakeRejection} with the generic
+	 * {@link HandshakeRejection#INTERNAL_ERROR} reason.
 	 *
 	 * @since Envoy Common v0.3-alpha
 	 */
-	public HandshakeRejection() { super(""); }
+	public HandshakeRejection() { super(INTERNAL_ERROR); }
 
 	/**
 	 * Creates an instance of {@link HandshakeRejection}.