diff --git a/src/mibew/libs/classes/Mibew/Authentication/AuthenticationManager.php b/src/mibew/libs/classes/Mibew/Authentication/AuthenticationManager.php
index 24446e4a..06d77d51 100644
--- a/src/mibew/libs/classes/Mibew/Authentication/AuthenticationManager.php
+++ b/src/mibew/libs/classes/Mibew/Authentication/AuthenticationManager.php
@@ -20,6 +20,7 @@
 namespace Mibew\Authentication;
 
 use Mibew\EventDispatcher\EventDispatcher;
+use Mibew\EventDispatcher\Events;
 use Mibew\Http\CookieFactory;
 use Mibew\Http\CookieFactoryAwareInterface;
 use Symfony\Component\HttpFoundation\Request;
@@ -82,12 +83,8 @@ class AuthenticationManager implements AuthenticationManagerInterface, CookieFac
     /**
      * {@inheritdoc}
      *
-     * Triggers 'operatorAuthenticate' event if operator is not authenticated by
-     * the system and pass to it an associative array with following items:
-     *  - 'operator': if a plugin has extracted operator from the request it
-     *    should set operator's data to this field.
-     *  - 'request': {@link Request}, incoming request. Can be used by a plugin
-     *    to extract an operator.
+     * Triggers {@link \Mibew\EventDispatcher\Events::OPERATOR_AUTHENTICATE}
+     * event.
      */
     public function setOperatorFromRequest(Request $request)
     {
@@ -123,7 +120,7 @@ class AuthenticationManager implements AuthenticationManagerInterface, CookieFac
             'request' => $request,
         );
         $dispatcher = EventDispatcher::getInstance();
-        $dispatcher->triggerEvent('operatorAuthenticate', $args);
+        $dispatcher->triggerEvent(Events::OPERATOR_AUTHENTICATE, $args);
 
         if (!empty($args['operator'])) {
             // Cache operator in the session
@@ -210,10 +207,7 @@ class AuthenticationManager implements AuthenticationManagerInterface, CookieFac
     /**
      * {@inheritdoc}
      *
-     * Triggers 'operatorLogin' event after operator logged in and pass to it an
-     * associative array with following items:
-     *  - 'operator': array of the logged in operator info;
-     *  - 'remember': boolean, indicates if system should remember operator.
+     * Triggers {@link \Mibew\EventDispatcher\Events::OPERATOR_LOGIN} event.
      */
     public function loginOperator($operator, $remember)
     {
@@ -228,13 +222,13 @@ class AuthenticationManager implements AuthenticationManagerInterface, CookieFac
             'remember' => $remember,
         );
         $dispatcher = EventDispatcher::getInstance();
-        $dispatcher->triggerEvent('operatorLogin', $args);
+        $dispatcher->triggerEvent(Events::OPERATOR_LOGIN, $args);
     }
 
     /**
      * {@inheritdoc}
      *
-     * Triggers 'operatorLogout' event after operator logged out.
+     * Triggers {@link \Mibew\EventDispatcher\Events::OPERATOR_LOGOUT} event.
      */
     public function logoutOperator()
     {
@@ -246,6 +240,6 @@ class AuthenticationManager implements AuthenticationManagerInterface, CookieFac
 
         // Trigger logout event
         $dispatcher = EventDispatcher::getInstance();
-        $dispatcher->triggerEvent('operatorLogout');
+        $dispatcher->triggerEvent(Events::OPERATOR_LOGOUT);
     }
 }
diff --git a/src/mibew/libs/classes/Mibew/EventDispatcher/Events.php b/src/mibew/libs/classes/Mibew/EventDispatcher/Events.php
new file mode 100644
index 00000000..87460b08
--- /dev/null
+++ b/src/mibew/libs/classes/Mibew/EventDispatcher/Events.php
@@ -0,0 +1,68 @@
+<?php
+/*
+ * This file is a part of Mibew Messenger.
+ *
+ * Copyright 2005-2014 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace Mibew\EventDispatcher;
+
+/**
+ * This class contains a list of events that are present in the system.
+ */
+final class Events
+{
+    /**
+     * An operator cannot be authenticated.
+     *
+     * This event is triggered if an operator cannot be authenticated by the
+     * system. It provides an ability for plugins to implement custom
+     * authentication logic. An associative array with the following items is
+     * passed to the event handlers:
+     *  - "operator": array, if a plugin has extracted operator from the request
+     *    it should set operator's data to this field.
+     *  - "request": {@link \Symfony\Component\HttpFoundation\Request},
+     *    incoming request. Can be used by a plugin to extract an operator.
+     */
+    const OPERATOR_AUTHENTICATE = 'operatorAuthenticate';
+
+    /**
+     * An operator logged in.
+     *
+     * This event is triggered after an operator logged in using system login
+     * form. An associative array with the following items is passed to the
+     * event handlers:
+     *  - "operator": array of the logged in operator info;
+     *  - "remember": boolean, indicates if system should remember operator.
+     */
+    const OPERATOR_LOGIN = 'operatorLogin';
+
+    /**
+     * An operator logged out.
+     *
+     * This event is triggered after an operator is logged out.
+     */
+    const OPERATOR_LOGOUT = 'operatorLogout';
+
+    /**
+     * An operator is deleted.
+     *
+     * This event is triggered after an operator has been deleted. An
+     * associative array with the following items is passed to the event
+     * handlers:
+     *  - "id": int, deleted operator ID.
+     */
+    const OPERATOR_DELETE = 'operatorDelete';
+}
diff --git a/src/mibew/libs/operator.php b/src/mibew/libs/operator.php
index 13e6d321..03e8f5a2 100644
--- a/src/mibew/libs/operator.php
+++ b/src/mibew/libs/operator.php
@@ -20,6 +20,7 @@
 // Import namespaces and classes of the core
 use Mibew\Database;
 use Mibew\EventDispatcher\EventDispatcher;
+use Mibew\EventDispatcher\Events;
 use Mibew\Settings;
 use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
 
@@ -410,9 +411,7 @@ function create_operator(
  *
  * This function remove operator and associations with groups for this operator
  * from datatabse.
- * It triggers 'operatorDelete' event and pass to event listeners associative
- * array with following keys:
- *  - 'id': int, deleted operator ID.
+ * It triggers {@link \Mibew\EventDispatcher\Events::OPERATOR_DELETE} event.
  *
  * @param int $operator_id Operator ID
  */
@@ -431,7 +430,7 @@ function delete_operator($operator_id)
     // Trigger 'operatorDelete' event
     $dispatcher = EventDispatcher::getInstance();
     $args = array('id' => $operator_id);
-    $dispatcher->triggerEvent('operatorDelete', $args);
+    $dispatcher->triggerEvent(Events::OPERATOR_DELETE, $args);
 }
 
 /**