diff --git a/plugin/advancedsubscription/ajax/advsub.ajax.php b/plugin/advancedsubscription/ajax/advsub.ajax.php
index c788da6f99..5d31325934 100644
--- a/plugin/advancedsubscription/ajax/advsub.ajax.php
+++ b/plugin/advancedsubscription/ajax/advsub.ajax.php
@@ -12,7 +12,9 @@
 require_once __DIR__ . '/../config.php';
 
 $plugin = AdvancedSubscriptionPlugin::create();
+// Get validation hash
 $hash = Security::remove_XSS($_REQUEST['v']);
+// Get data from request (GET or POST)
 $data['a'] = Security::remove_XSS($_REQUEST['a']);
 $data['s'] = intval($_REQUEST['s']);
 $data['current_user_id'] = intval($_REQUEST['current_user_id']);
@@ -21,9 +23,10 @@ $data['q'] = intval($_REQUEST['q']);
 $data['e'] = intval($_REQUEST['e']);
 $data['is_connected'] = isset($_REQUEST['is_connected']) ? boolval($_REQUEST['is_connected']) : false;
 $data['profile_completed'] = isset($_REQUEST['profile_completed']) ? floatval($_REQUEST['profile_completed']) : 0;
-$verified = $plugin->checkHash($data, $hash) || $data['a'] == 'subscribe';
 // Init result array
-$result = array('error' => true, 'errorMessage' => 'There was an error');
+$result = array('error' => true, 'errorMessage' => get_lang('ThereWasAnError'));
+// Check if data is valid or is for start subscription
+$verified = $plugin->checkHash($data, $hash) || $data['a'] == 'subscribe';
 if ($verified) {
     switch($data['a']) {
         case 'check': // Check minimum requirements
@@ -42,10 +45,12 @@ if ($verified) {
             }
             break;
         case 'subscribe': // Subscription
-            $bossId = UserManager::getStudentBoss($data['u']);
+            // Start subscription to queue
             $res = AdvancedSubscriptionPlugin::create()->startSubscription($data['u'], $data['s'], $data);
+            // Check if queue subscription was successful
             if ($res === true) {
-                // send mail to superior
+                // Prepare data
+                // Get session data
                 $sessionArray = api_get_session_info($data['s']);
                 $extraSession = new ExtraFieldValue('session');
                 $var = $extraSession->get_values_by_handler_and_field_variable($data['s'], 'description');
@@ -58,20 +63,24 @@ if ($verified) {
                 $sessionArray['publication_end_date'] = $var['field_value'];
                 $var = $extraSession->get_values_by_handler_and_field_variable($data['s'], 'recommended_number_of_participants');
                 $sessionArray['recommended_number_of_participants'] = $var['field_valiue'];
+                // Get student data
                 $studentArray = api_get_user_info($data['u']);
                 $studentArray['picture'] = UserManager::get_user_picture_path_by_id($studentArray['user_id'], 'web', false, true);
                 $studentArray['picture'] = UserManager::get_picture_user($studentArray['user_id'], $studentArray['picture']['file'], 22, USER_IMAGE_SIZE_MEDIUM);
+                // Get superior data if exist
                 $superiorId = UserManager::getStudentBoss($data['u']);
                 if (!empty($superiorId)) {
                     $superiorArray = api_get_user_info($superiorId);
                 } else {
                     $superiorArray = null;
                 }
+                // Get admin data
                 $adminsArray = UserManager::get_all_administrators();
                 foreach ($adminsArray as &$admin) {
                     $admin['complete_name'] = $admin['lastname'] . ', ' . $admin['firstname'];
                 }
                 unset($admin);
+                // Set data
                 $data['a'] = 'confirm';
                 $data['student'] = $studentArray;
                 $data['superior'] = $superiorArray;
@@ -79,15 +88,23 @@ if ($verified) {
                 $data['session'] = $sessionArray;
                 $data['signature'] = api_get_setting('Institution');
 
-                if (empty($superiorId)) { // Does not have boss
+                // Check if student boss exists
+                if (empty($superiorId)) {
+                    // Student boss does not exist
+                    // Update status to accepted by boss
                     $res = $plugin->updateQueueStatus($data, ADV_SUB_QUEUE_STATUS_BOSS_APPROVED);
                     if (!empty($res)) {
-                        $data['admin_view_url'] = api_get_path(WEB_PLUGIN_PATH) . 'advancedsubscription/src/admin_view.php?s=' . $data['s'];
+                        // Prepare admin url
+                        $data['admin_view_url'] = api_get_path(WEB_PLUGIN_PATH) .
+                            'advancedsubscription/src/admin_view.php?s=' . $data['s'];
+                        // Send mails
                         $result['mailIds'] = $plugin->sendMail($data, ADV_SUB_ACTION_STUDENT_REQUEST_NO_BOSS);
+                        // Check if mails were sent
                         if (!empty($result['mailIds'])) {
                             $result['error'] = false;
                             $result['errorMessage'] = 'No error';
                             $result['pass'] = true;
+                            // Check if exist an email to render
                             if (isset($result['mailIds']['render'])) {
                                 // Render mail
                                 $message = MessageManager::get_message_by_id($result['mailIds']['render']);
@@ -98,15 +115,21 @@ if ($verified) {
                         }
                     }
                 } else {
+                    // Student boss does exist
+                    // Get url to be accepted by boss
                     $data['e'] = ADV_SUB_QUEUE_STATUS_BOSS_APPROVED;
                     $data['student']['acceptUrl'] = $plugin->getQueueUrl($data);
+                    // Get url to be rejected by boss
                     $data['e'] = ADV_SUB_QUEUE_STATUS_BOSS_DISAPPROVED;
                     $data['student']['rejectUrl'] = $plugin->getQueueUrl($data);
+                    // Send mails
                     $result['mailIds'] = $plugin->sendMail($data, ADV_SUB_ACTION_STUDENT_REQUEST);
+                    // Check if mails were sent
                     if (!empty($result['mailIds'])) {
                         $result['error'] = false;
                         $result['errorMessage'] = 'No error';
                         $result['pass'] = true;
+                        // Check if exist an email to render
                         if (isset($result['mailIds']['render'])) {
                             // Render mail
                             $message = MessageManager::get_message_by_id($result['mailIds']['render']);
@@ -127,9 +150,13 @@ if ($verified) {
 
             break;
         case 'confirm':
+            // Check if is set new status
             if (isset($data['e'])) {
+                // Update queue status
                 $res = $plugin->updateQueueStatus($data, $data['e']);
                 if ($res === true) {
+                    // Prepare data
+                    // Prepare session data
                     $sessionArray = api_get_session_info($data['s']);
                     $extraSession = new ExtraFieldValue('session');
                     $var = $extraSession->get_values_by_handler_and_field_variable($data['s'], 'description');
@@ -142,27 +169,33 @@ if ($verified) {
                     $sessionArray['publication_end_date'] = $var['field_value'];
                     $var = $extraSession->get_values_by_handler_and_field_variable($data['s'], 'recommended_number_of_participants');
                     $sessionArray['recommended_number_of_participants'] = $var['field_valiue'];
+                    // Prepare student data
                     $studentArray = api_get_user_info($data['u']);
                     $studentArray['picture'] = UserManager::get_user_picture_path_by_id($studentArray['user_id'], 'web', false, true);
                     $studentArray['picture'] = UserManager::get_picture_user($studentArray['user_id'], $studentArray['picture']['file'], 22, USER_IMAGE_SIZE_MEDIUM);
+                    // Prepare superior data
                     $superiorId = UserManager::getStudentBoss($data['u']);
                     if (!empty($superiorId)) {
                         $superiorArray = api_get_user_info($superiorId);
                     } else {
                         $superiorArray = null;
                     }
+                    // Prepare admin data
                     $adminsArray = UserManager::get_all_administrators();
                     foreach ($adminsArray as &$admin) {
                         $admin['complete_name'] = $admin['lastname'] . ', ' . $admin['firstname'];
                     }
                     unset($admin);
+                    // Set data
                     $data['student'] = $studentArray;
                     $data['superior'] = $superiorArray;
                     $data['admins'] = $adminsArray;
                     $data['session'] = $sessionArray;
                     $data['signature'] = api_get_setting('Institution');
                     $data['admin_view_url'] = api_get_path(WEB_PLUGIN_PATH) . 'advancedsubscription/src/admin_view.php?s=' . $data['s'];
+                    // Check if exist and action in data
                     if (empty($data['action'])) {
+                        // set action in data by new status
                         switch ($data['e']) {
                             case ADV_SUB_QUEUE_STATUS_BOSS_APPROVED:
                                 $data['action'] = ADV_SUB_ACTION_SUPERIOR_APPROVE;
@@ -186,10 +219,13 @@ if ($verified) {
                         SessionManager::suscribe_users_to_session($data['s'], array($data['u']), null, false);
                     }
 
+                    // Send mails
                     $result['mailIds'] = $plugin->sendMail($data, $data['action']);
+                    // Check if mails were sent
                     if (!empty($result['mailIds'])) {
                         $result['error'] = false;
                         $result['errorMessage'] = 'User has been processed';
+                        // Check if exist mail to render
                         if (isset($result['mailIds']['render'])) {
                             // Render mail
                             $message = MessageManager::get_message_by_id($result['mailIds']['render']);
@@ -208,4 +244,5 @@ if ($verified) {
     }
 }
 
+// Echo result as json
 echo json_encode($result);