diff --git a/includes/helper/graph_helper.php b/includes/helper/graph_helper.php
index 180d1ef9..42a6c07a 100644
--- a/includes/helper/graph_helper.php
+++ b/includes/helper/graph_helper.php
@@ -7,7 +7,7 @@
  * @param unknown $colors colors for the data rows
  * @param unknown $data the data
  */
-function bargraph($id, $key, $row_names, $colors, $data) {
+function bargraph($dom_id, $key, $row_names, $colors, $data) {
   $labels = [];
   foreach ($data as $dataset) {
     $labels[] = $dataset[$key];
@@ -26,10 +26,10 @@ function bargraph($id, $key, $row_names, $colors, $data) {
     ];
   }
   
-  return '<canvas id="' . $id . '" style="width: 100%; height: 300px;"></canvas>
+  return '<canvas id="' . $dom_id . '" style="width: 100%; height: 300px;"></canvas>
       <script type="text/javascript">
       $(function(){
-        var ctx = $("#' . $id . '").get(0).getContext("2d");
+        var ctx = $("#' . $dom_id . '").get(0).getContext("2d");
         var chart = new Chart(ctx).Bar(' . json_encode([
       'labels' => $labels,
       'datasets' => $datasets 
diff --git a/includes/model/AngelType_model.php b/includes/model/AngelType_model.php
index 47c13667..21ab3bf2 100644
--- a/includes/model/AngelType_model.php
+++ b/includes/model/AngelType_model.php
@@ -133,11 +133,11 @@ function AngelType_ids() {
 /**
  * Returns angelType by id.
  *
- * @param $id angelType
+ * @param $angeltype_id angelType
  *          ID
  */
-function AngelType($id) {
-  $angelType_source = sql_select("SELECT * FROM `AngelTypes` WHERE `id`='" . sql_escape($id) . "' LIMIT 1");
+function AngelType($angeltype_id) {
+  $angelType_source = sql_select("SELECT * FROM `AngelTypes` WHERE `id`='" . sql_escape($angeltype_id) . "' LIMIT 1");
   if ($angelType_source === false) {
     return false;
   }
diff --git a/includes/model/Message_model.php b/includes/model/Message_model.php
index 92b76a80..0195fbea 100644
--- a/includes/model/Message_model.php
+++ b/includes/model/Message_model.php
@@ -10,11 +10,11 @@ function Message_ids() {
 /**
  * Returns message by id.
  *
- * @param $id message
+ * @param $message_id message
  *          ID
  */
-function Message($id) {
-  $message_source = sql_select("SELECT * FROM `Messages` WHERE `id`='" . sql_escape($id) . "' LIMIT 1");
+function Message($message_id) {
+  $message_source = sql_select("SELECT * FROM `Messages` WHERE `id`='" . sql_escape($message_id) . "' LIMIT 1");
   if ($message_source === false) {
     return false;
   }
@@ -29,19 +29,19 @@ function Message($id) {
  * TODO: global $user con not be used in model!
  * send message
  *
- * @param $id User
+ * @param $receiver_user_id User
  *          ID of Reciever
  * @param $text Text
  *          of Message
  */
-function Message_send($id, $text) {
+function Message_send($receiver_user_id, $text) {
   global $user;
   
   $text = preg_replace("/([^\p{L}\p{P}\p{Z}\p{N}\n]{1,})/ui", '', strip_tags($text));
-  $to = preg_replace("/([^0-9]{1,})/ui", '', strip_tags($id));
+  $receiver_user_id = preg_replace("/([^0-9]{1,})/ui", '', strip_tags($receiver_user_id));
   
-  if (($text != "" && is_numeric($to)) && (sql_num_query("SELECT * FROM `User` WHERE `UID`='" . sql_escape($to) . "' AND NOT `UID`='" . sql_escape($user['UID']) . "' LIMIT 1") > 0)) {
-    sql_query("INSERT INTO `Messages` SET `Datum`='" . sql_escape(time()) . "', `SUID`='" . sql_escape($user['UID']) . "', `RUID`='" . sql_escape($to) . "', `Text`='" . sql_escape($text) . "'");
+  if (($text != "" && is_numeric($receiver_user_id)) && (sql_num_query("SELECT * FROM `User` WHERE `UID`='" . sql_escape($receiver_user_id) . "' AND NOT `UID`='" . sql_escape($user['UID']) . "' LIMIT 1") > 0)) {
+    sql_query("INSERT INTO `Messages` SET `Datum`='" . sql_escape(time()) . "', `SUID`='" . sql_escape($user['UID']) . "', `RUID`='" . sql_escape($receiver_user_id) . "', `Text`='" . sql_escape($text) . "'");
     return true;
   } else {
     return false;
diff --git a/includes/model/Room_model.php b/includes/model/Room_model.php
index 1768b61b..4d03260a 100644
--- a/includes/model/Room_model.php
+++ b/includes/model/Room_model.php
@@ -34,10 +34,10 @@ function Room_create($name, $from_frab, $public) {
 /**
  * Returns room by id.
  *
- * @param $id RID          
+ * @param $room_id RID          
  */
-function Room($id) {
-  $room_source = sql_select("SELECT * FROM `Room` WHERE `RID`='" . sql_escape($id) . "' AND `show` = 'Y'");
+function Room($room_id) {
+  $room_source = sql_select("SELECT * FROM `Room` WHERE `RID`='" . sql_escape($room_id) . "' AND `show` = 'Y'");
   
   if ($room_source === false) {
     return false;
diff --git a/includes/model/Shifts_model.php b/includes/model/Shifts_model.php
index cca5139d..2f90ae48 100644
--- a/includes/model/Shifts_model.php
+++ b/includes/model/Shifts_model.php
@@ -229,16 +229,16 @@ function Shifts_filtered() {
 /**
  * Returns Shift by id.
  *
- * @param $id Shift
+ * @param $shift_id Shift
  *          ID
  */
-function Shift($id) {
+function Shift($shift_id) {
   $shifts_source = sql_select("
       SELECT `Shifts`.*, `ShiftTypes`.`name`
       FROM `Shifts` 
       JOIN `ShiftTypes` ON (`ShiftTypes`.`id` = `Shifts`.`shifttype_id`)
-      WHERE `SID`='" . sql_escape($id) . "'");
-  $shiftsEntry_source = sql_select("SELECT `id`, `TID` , `UID` , `freeloaded` FROM `ShiftEntry` WHERE `SID`='" . sql_escape($id) . "'");
+      WHERE `SID`='" . sql_escape($shift_id) . "'");
+  $shiftsEntry_source = sql_select("SELECT `id`, `TID` , `UID` , `freeloaded` FROM `ShiftEntry` WHERE `SID`='" . sql_escape($shift_id) . "'");
   
   if ($shifts_source === false) {
     return false;
@@ -249,14 +249,14 @@ function Shift($id) {
     $result['ShiftEntry'] = $shiftsEntry_source;
     $result['NeedAngels'] = [];
     
-    $temp = NeededAngelTypes_by_shift($id);
+    $temp = NeededAngelTypes_by_shift($shift_id);
     foreach ($temp as $e) {
-      $result['NeedAngels'][] = array(
+      $result['NeedAngels'][] = [
           'TID' => $e['angel_type_id'],
           'count' => $e['count'],
           'restricted' => $e['restricted'],
           'taken' => $e['taken'] 
-      );
+      ];
     }
     
     return $result;
diff --git a/includes/model/User_model.php b/includes/model/User_model.php
index 3d5416da..7f9170df 100644
--- a/includes/model/User_model.php
+++ b/includes/model/User_model.php
@@ -160,10 +160,10 @@ function User_validate_Nick($nick) {
 /**
  * Returns user by id.
  *
- * @param $id UID          
+ * @param $user_id UID          
  */
-function User($id) {
-  $user_source = sql_select("SELECT * FROM `User` WHERE `UID`='" . sql_escape($id) . "' LIMIT 1");
+function User($user_id) {
+  $user_source = sql_select("SELECT * FROM `User` WHERE `UID`='" . sql_escape($user_id) . "' LIMIT 1");
   if ($user_source === false) {
     return false;
   }
@@ -177,10 +177,10 @@ function User($id) {
  * TODO: Merge into normal user function
  * Returns user by id (limit informations.
  *
- * @param $id UID          
+ * @param $user_id UID          
  */
-function mUser_Limit($id) {
-  $user_source = sql_select("SELECT `UID`, `Nick`, `Name`, `Vorname`, `Telefon`, `DECT`, `Handy`, `email`, `jabber` FROM `User` WHERE `UID`='" . sql_escape($id) . "' LIMIT 1");
+function mUser_Limit($user_id) {
+  $user_source = sql_select("SELECT `UID`, `Nick`, `Name`, `Vorname`, `Telefon`, `DECT`, `Handy`, `email`, `jabber` FROM `User` WHERE `UID`='" . sql_escape($user_id) . "' LIMIT 1");
   if ($user_source === false) {
     return false;
   }
diff --git a/includes/pages/admin_active.php b/includes/pages/admin_active.php
index 83f99d5a..733bd506 100644
--- a/includes/pages/admin_active.php
+++ b/includes/pages/admin_active.php
@@ -63,40 +63,40 @@ function admin_active() {
   }
   
   if (isset($_REQUEST['active']) && preg_match("/^[0-9]+$/", $_REQUEST['active'])) {
-    $id = $_REQUEST['active'];
-    $user_source = User($id);
+    $user_id = $_REQUEST['active'];
+    $user_source = User($user_id);
     if ($user_source != null) {
-      sql_query("UPDATE `User` SET `Aktiv`=1 WHERE `UID`='" . sql_escape($id) . "' LIMIT 1");
+      sql_query("UPDATE `User` SET `Aktiv`=1 WHERE `UID`='" . sql_escape($user_id) . "' LIMIT 1");
       engelsystem_log("User " . User_Nick_render($user_source) . " is active now.");
       $msg = success(_("Angel has been marked as active."), true);
     } else {
       $msg = error(_("Angel not found."), true);
     }
   } elseif (isset($_REQUEST['not_active']) && preg_match("/^[0-9]+$/", $_REQUEST['not_active'])) {
-    $id = $_REQUEST['not_active'];
-    $user_source = User($id);
+    $user_id = $_REQUEST['not_active'];
+    $user_source = User($user_id);
     if ($user_source != null) {
-      sql_query("UPDATE `User` SET `Aktiv`=0 WHERE `UID`='" . sql_escape($id) . "' LIMIT 1");
+      sql_query("UPDATE `User` SET `Aktiv`=0 WHERE `UID`='" . sql_escape($user_id) . "' LIMIT 1");
       engelsystem_log("User " . User_Nick_render($user_source) . " is NOT active now.");
       $msg = success(_("Angel has been marked as not active."), true);
     } else {
       $msg = error(_("Angel not found."), true);
     }
   } elseif (isset($_REQUEST['tshirt']) && preg_match("/^[0-9]+$/", $_REQUEST['tshirt'])) {
-    $id = $_REQUEST['tshirt'];
-    $user_source = User($id);
+    $user_id = $_REQUEST['tshirt'];
+    $user_source = User($user_id);
     if ($user_source != null) {
-      sql_query("UPDATE `User` SET `Tshirt`=1 WHERE `UID`='" . sql_escape($id) . "' LIMIT 1");
+      sql_query("UPDATE `User` SET `Tshirt`=1 WHERE `UID`='" . sql_escape($user_id) . "' LIMIT 1");
       engelsystem_log("User " . User_Nick_render($user_source) . " has tshirt now.");
       $msg = success(_("Angel has got a t-shirt."), true);
     } else {
       $msg = error("Angel not found.", true);
     }
   } elseif (isset($_REQUEST['not_tshirt']) && preg_match("/^[0-9]+$/", $_REQUEST['not_tshirt'])) {
-    $id = $_REQUEST['not_tshirt'];
-    $user_source = User($id);
+    $user_id = $_REQUEST['not_tshirt'];
+    $user_source = User($user_id);
     if ($user_source != null) {
-      sql_query("UPDATE `User` SET `Tshirt`=0 WHERE `UID`='" . sql_escape($id) . "' LIMIT 1");
+      sql_query("UPDATE `User` SET `Tshirt`=0 WHERE `UID`='" . sql_escape($user_id) . "' LIMIT 1");
       engelsystem_log("User " . User_Nick_render($user_source) . " has NO tshirt.");
       $msg = success(_("Angel has got no t-shirt."), true);
     } else {
diff --git a/includes/pages/admin_arrive.php b/includes/pages/admin_arrive.php
index 932929c2..4a1ee8d7 100644
--- a/includes/pages/admin_arrive.php
+++ b/includes/pages/admin_arrive.php
@@ -12,10 +12,10 @@ function admin_arrive() {
   }
   
   if (isset($_REQUEST['reset']) && preg_match("/^[0-9]*$/", $_REQUEST['reset'])) {
-    $id = $_REQUEST['reset'];
-    $user_source = User($id);
+    $user_id = $_REQUEST['reset'];
+    $user_source = User($user_id);
     if ($user_source != null) {
-      sql_query("UPDATE `User` SET `Gekommen`=0, `arrival_date` = NULL WHERE `UID`='" . sql_escape($id) . "' LIMIT 1");
+      sql_query("UPDATE `User` SET `Gekommen`=0, `arrival_date` = NULL WHERE `UID`='" . sql_escape($user_id) . "' LIMIT 1");
       engelsystem_log("User set to not arrived: " . User_Nick_render($user_source));
       success(_("Reset done. Angel has not arrived."));
       redirect(user_link($user_source));
@@ -23,10 +23,10 @@ function admin_arrive() {
       $msg = error(_("Angel not found."), true);
     }
   } elseif (isset($_REQUEST['arrived']) && preg_match("/^[0-9]*$/", $_REQUEST['arrived'])) {
-    $id = $_REQUEST['arrived'];
-    $user_source = User($id);
+    $user_id = $_REQUEST['arrived'];
+    $user_source = User($user_id);
     if ($user_source != null) {
-      sql_query("UPDATE `User` SET `Gekommen`=1, `arrival_date`='" . time() . "' WHERE `UID`='" . sql_escape($id) . "' LIMIT 1");
+      sql_query("UPDATE `User` SET `Gekommen`=1, `arrival_date`='" . time() . "' WHERE `UID`='" . sql_escape($user_id) . "' LIMIT 1");
       engelsystem_log("User set has arrived: " . User_Nick_render($user_source));
       success(_("Angel has been marked as arrived."));
       redirect(user_link($user_source));
diff --git a/includes/pages/admin_groups.php b/includes/pages/admin_groups.php
index d26e6de7..69b6bf39 100644
--- a/includes/pages/admin_groups.php
+++ b/includes/pages/admin_groups.php
@@ -35,15 +35,15 @@ function admin_groups() {
     switch ($_REQUEST["action"]) {
       case 'edit':
         if (isset($_REQUEST['id']) && preg_match("/^-[0-9]{1,11}$/", $_REQUEST['id'])) {
-          $id = $_REQUEST['id'];
+          $group_id = $_REQUEST['id'];
         } else {
           return error("Incomplete call, missing Groups ID.", true);
         }
         
-        $room = sql_select("SELECT * FROM `Groups` WHERE `UID`='" . sql_escape($id) . "' LIMIT 1");
-        if (count($room) > 0) {
-          list($room) = $room;
-          $privileges = sql_select("SELECT `Privileges`.*, `GroupPrivileges`.`group_id` FROM `Privileges` LEFT OUTER JOIN `GroupPrivileges` ON (`Privileges`.`id` = `GroupPrivileges`.`privilege_id` AND `GroupPrivileges`.`group_id`='" . sql_escape($id) . "') ORDER BY `Privileges`.`name`");
+        $group = sql_select("SELECT * FROM `Groups` WHERE `UID`='" . sql_escape($group_id) . "' LIMIT 1");
+        if (count($group) > 0) {
+          list($group) = $group;
+          $privileges = sql_select("SELECT `Privileges`.*, `GroupPrivileges`.`group_id` FROM `Privileges` LEFT OUTER JOIN `GroupPrivileges` ON (`Privileges`.`id` = `GroupPrivileges`.`privilege_id` AND `GroupPrivileges`.`group_id`='" . sql_escape($group_id) . "') ORDER BY `Privileges`.`name`");
           $privileges_html = "";
           $privileges_form = [];
           foreach ($privileges as $priv) {
@@ -53,7 +53,7 @@ function admin_groups() {
           
           $privileges_form[] = form_submit('submit', _("Save"));
           $html .= page_with_title(_("Edit group"), [
-              form($privileges_form, page_link_to('admin_groups') . '&action=save&id=' . $id) 
+              form($privileges_form, page_link_to('admin_groups') . '&action=save&id=' . $group_id) 
           ]);
         } else {
           return error("No Group found.", true);
@@ -62,29 +62,29 @@ function admin_groups() {
       
       case 'save':
         if (isset($_REQUEST['id']) && preg_match("/^-[0-9]{1,11}$/", $_REQUEST['id'])) {
-          $id = $_REQUEST['id'];
+          $group_id = $_REQUEST['id'];
         } else {
           return error("Incomplete call, missing Groups ID.", true);
         }
         
-        $room = sql_select("SELECT * FROM `Groups` WHERE `UID`='" . sql_escape($id) . "' LIMIT 1");
+        $group = sql_select("SELECT * FROM `Groups` WHERE `UID`='" . sql_escape($group_id) . "' LIMIT 1");
         if (! is_array($_REQUEST['privileges'])) {
           $_REQUEST['privileges'] = [];
         }
-        if (count($room) > 0) {
-          list($room) = $room;
-          sql_query("DELETE FROM `GroupPrivileges` WHERE `group_id`='" . sql_escape($id) . "'");
+        if (count($group) > 0) {
+          list($group) = $group;
+          sql_query("DELETE FROM `GroupPrivileges` WHERE `group_id`='" . sql_escape($group_id) . "'");
           $privilege_names = [];
           foreach ($_REQUEST['privileges'] as $priv) {
             if (preg_match("/^[0-9]{1,}$/", $priv)) {
               $group_privileges_source = sql_select("SELECT * FROM `Privileges` WHERE `id`='" . sql_escape($priv) . "' LIMIT 1");
               if (count($group_privileges_source) > 0) {
-                sql_query("INSERT INTO `GroupPrivileges` SET `group_id`='" . sql_escape($id) . "', `privilege_id`='" . sql_escape($priv) . "'");
+                sql_query("INSERT INTO `GroupPrivileges` SET `group_id`='" . sql_escape($group_id) . "', `privilege_id`='" . sql_escape($priv) . "'");
                 $privilege_names[] = $group_privileges_source[0]['name'];
               }
             }
           }
-          engelsystem_log("Group privileges of group " . $room['Name'] . " edited: " . join(", ", $privilege_names));
+          engelsystem_log("Group privileges of group " . $group['Name'] . " edited: " . join(", ", $privilege_names));
           redirect(page_link_to("admin_groups"));
         } else {
           return error("No Group found.", true);
diff --git a/includes/pages/admin_news.php b/includes/pages/admin_news.php
index 192f3cce..af7046c9 100644
--- a/includes/pages/admin_news.php
+++ b/includes/pages/admin_news.php
@@ -8,12 +8,12 @@ function admin_news() {
   } else {
     $html = '<div class="col-md-12"><h1>' . _("Edit news entry") . '</h1>' . msg();
     if (isset($_REQUEST['id']) && preg_match("/^[0-9]{1,11}$/", $_REQUEST['id'])) {
-      $id = $_REQUEST['id'];
+      $news_id = $_REQUEST['id'];
     } else {
       return error("Incomplete call, missing News ID.", true);
     }
     
-    $news = sql_select("SELECT * FROM `News` WHERE `ID`='" . sql_escape($id) . "' LIMIT 1");
+    $news = sql_select("SELECT * FROM `News` WHERE `ID`='" . sql_escape($news_id) . "' LIMIT 1");
     if (count($news) > 0) {
       switch ($_REQUEST["action"]) {
         default:
@@ -33,9 +33,9 @@ function admin_news() {
               form_textarea('eText', _("Message"), $news['Text']),
               form_checkbox('eTreffen', _("Meeting"), $news['Treffen'] == 1, 1),
               form_submit('submit', _("Save")) 
-          ], page_link_to('admin_news&action=save&id=' . $id));
+          ], page_link_to('admin_news&action=save&id=' . $news_id));
           
-          $html .= '<a class="btn btn-danger" href="' . page_link_to('admin_news&action=delete&id=' . $id) . '"><span class="glyphicon glyphicon-trash"></span> ' . _("Delete") . '</a>';
+          $html .= '<a class="btn btn-danger" href="' . page_link_to('admin_news&action=delete&id=' . $news_id) . '"><span class="glyphicon glyphicon-trash"></span> ' . _("Delete") . '</a>';
           break;
         
         case 'save':
@@ -47,7 +47,7 @@ function admin_news() {
               `Text`='" . sql_escape($_POST["eText"]) . "', 
               `UID`='" . sql_escape($user['UID']) . "', 
               `Treffen`='" . sql_escape($_POST["eTreffen"]) . "' 
-              WHERE `ID`='" . sql_escape($id) . "'");
+              WHERE `ID`='" . sql_escape($news_id) . "'");
           engelsystem_log("News updated: " . $_POST["eBetreff"]);
           success(_("News entry updated."));
           redirect(page_link_to("news"));
@@ -56,7 +56,7 @@ function admin_news() {
         case 'delete':
           list($news) = $news;
           
-          sql_query("DELETE FROM `News` WHERE `ID`='" . sql_escape($id) . "' LIMIT 1");
+          sql_query("DELETE FROM `News` WHERE `ID`='" . sql_escape($news_id) . "' LIMIT 1");
           engelsystem_log("News deleted: " . $news['Betreff']);
           success(_("News entry deleted."));
           redirect(page_link_to("news"));
diff --git a/includes/pages/admin_questions.php b/includes/pages/admin_questions.php
index 183f7944..f67c6ce8 100644
--- a/includes/pages/admin_questions.php
+++ b/includes/pages/admin_questions.php
@@ -83,17 +83,17 @@ function admin_questions() {
     switch ($_REQUEST['action']) {
       case 'answer':
         if (isset($_REQUEST['id']) && preg_match("/^[0-9]{1,11}$/", $_REQUEST['id'])) {
-          $id = $_REQUEST['id'];
+          $question_id = $_REQUEST['id'];
         } else {
           return error("Incomplete call, missing Question ID.", true);
         }
         
-        $question = sql_select("SELECT * FROM `Questions` WHERE `QID`='" . sql_escape($id) . "' LIMIT 1");
+        $question = sql_select("SELECT * FROM `Questions` WHERE `QID`='" . sql_escape($question_id) . "' LIMIT 1");
         if (count($question) > 0 && $question[0]['AID'] == null) {
           $answer = trim(preg_replace("/([^\p{L}\p{P}\p{Z}\p{N}\n]{1,})/ui", '', strip_tags($_REQUEST['answer'])));
           
           if ($answer != "") {
-            sql_query("UPDATE `Questions` SET `AID`='" . sql_escape($user['UID']) . "', `Answer`='" . sql_escape($answer) . "' WHERE `QID`='" . sql_escape($id) . "' LIMIT 1");
+            sql_query("UPDATE `Questions` SET `AID`='" . sql_escape($user['UID']) . "', `Answer`='" . sql_escape($answer) . "' WHERE `QID`='" . sql_escape($question_id) . "' LIMIT 1");
             engelsystem_log("Question " . $question[0]['Question'] . " answered: " . $answer);
             redirect(page_link_to("admin_questions"));
           } else {
@@ -105,14 +105,14 @@ function admin_questions() {
         break;
       case 'delete':
         if (isset($_REQUEST['id']) && preg_match("/^[0-9]{1,11}$/", $_REQUEST['id'])) {
-          $id = $_REQUEST['id'];
+          $question_id = $_REQUEST['id'];
         } else {
           return error("Incomplete call, missing Question ID.", true);
         }
         
-        $question = sql_select("SELECT * FROM `Questions` WHERE `QID`='" . sql_escape($id) . "' LIMIT 1");
+        $question = sql_select("SELECT * FROM `Questions` WHERE `QID`='" . sql_escape($question_id) . "' LIMIT 1");
         if (count($question) > 0) {
-          sql_query("DELETE FROM `Questions` WHERE `QID`='" . sql_escape($id) . "' LIMIT 1");
+          sql_query("DELETE FROM `Questions` WHERE `QID`='" . sql_escape($question_id) . "' LIMIT 1");
           engelsystem_log("Question deleted: " . $question[0]['Question']);
           redirect(page_link_to("admin_questions"));
         } else {
diff --git a/includes/pages/admin_rooms.php b/includes/pages/admin_rooms.php
index 3c26048a..155fd7b3 100644
--- a/includes/pages/admin_rooms.php
+++ b/includes/pages/admin_rooms.php
@@ -38,12 +38,12 @@ function admin_rooms() {
     if (test_request_int('id')) {
       $room = sql_select("SELECT * FROM `Room` WHERE `RID`='" . sql_escape($_REQUEST['id']) . "'");
       if (count($room) > 0) {
-        $id = $_REQUEST['id'];
+        $room_id = $_REQUEST['id'];
         $name = $room[0]['Name'];
         $from_pentabarf = $room[0]['FromPentabarf'];
         $public = $room[0]['show'];
         $number = $room[0]['Number'];
-        $needed_angeltypes = sql_select("SELECT * FROM `NeededAngelTypes` WHERE `room_id`='" . sql_escape($id) . "'");
+        $needed_angeltypes = sql_select("SELECT * FROM `NeededAngelTypes` WHERE `room_id`='" . sql_escape($room_id) . "'");
         foreach ($needed_angeltypes as $needed_angeltype) {
           $angeltypes_count[$needed_angeltype['angel_type_id']] = $needed_angeltype['count'];
         }
@@ -58,7 +58,7 @@ function admin_rooms() {
         
         if (isset($_REQUEST['name']) && strlen(strip_request_item('name')) > 0) {
           $name = strip_request_item('name');
-          if (isset($room) && sql_num_query("SELECT * FROM `Room` WHERE `Name`='" . sql_escape($name) . "' AND NOT `RID`=" . sql_escape($id)) > 0) {
+          if (isset($room) && sql_num_query("SELECT * FROM `Room` WHERE `Name`='" . sql_escape($name) . "' AND NOT `RID`=" . sql_escape($room_id)) > 0) {
             $valid = false;
             $msg .= error(_("This name is already in use."), true);
           }
@@ -95,18 +95,18 @@ function admin_rooms() {
         }
         
         if ($valid) {
-          if (isset($id)) {
-            sql_query("UPDATE `Room` SET `Name`='" . sql_escape($name) . "', `FromPentabarf`='" . sql_escape($from_pentabarf) . "', `show`='" . sql_escape($public) . "', `Number`='" . sql_escape($number) . "' WHERE `RID`='" . sql_escape($id) . "' LIMIT 1");
+          if (isset($room_id)) {
+            sql_query("UPDATE `Room` SET `Name`='" . sql_escape($name) . "', `FromPentabarf`='" . sql_escape($from_pentabarf) . "', `show`='" . sql_escape($public) . "', `Number`='" . sql_escape($number) . "' WHERE `RID`='" . sql_escape($room_id) . "' LIMIT 1");
             engelsystem_log("Room updated: " . $name . ", pentabarf import: " . $from_pentabarf . ", public: " . $public . ", number: " . $number);
           } else {
-            $id = Room_create($name, $from_pentabarf, $public, $number);
-            if ($id === false) {
+            $room_id = Room_create($name, $from_pentabarf, $public, $number);
+            if ($room_id === false) {
               engelsystem_error("Unable to create room.");
             }
             engelsystem_log("Room created: " . $name . ", pentabarf import: " . $from_pentabarf . ", public: " . $public . ", number: " . $number);
           }
           
-          sql_query("DELETE FROM `NeededAngelTypes` WHERE `room_id`='" . sql_escape($id) . "'");
+          sql_query("DELETE FROM `NeededAngelTypes` WHERE `room_id`='" . sql_escape($room_id) . "'");
           $needed_angeltype_info = array();
           foreach ($angeltypes_count as $angeltype_id => $angeltype_count) {
             $angeltype = AngelType($angeltype_id);
@@ -114,7 +114,7 @@ function admin_rooms() {
               engelsystem_error("Unable to load angeltype.");
             }
             if ($angeltype != null) {
-              sql_query("INSERT INTO `NeededAngelTypes` SET `room_id`='" . sql_escape($id) . "', `angel_type_id`='" . sql_escape($angeltype_id) . "', `count`='" . sql_escape($angeltype_count) . "'");
+              sql_query("INSERT INTO `NeededAngelTypes` SET `room_id`='" . sql_escape($room_id) . "', `angel_type_id`='" . sql_escape($angeltype_id) . "', `count`='" . sql_escape($angeltype_count) . "'");
               $needed_angeltype_info[] = $angeltype['name'] . ": " . $angeltype_count;
             }
           }
@@ -158,7 +158,7 @@ function admin_rooms() {
       ]);
     } elseif ($_REQUEST['show'] == 'delete') {
       if (isset($_REQUEST['ack'])) {
-        if (! Room_delete($id)) {
+        if (! Room_delete($room_id)) {
           engelsystem_error("Unable to delete room.");
         }
         
@@ -173,7 +173,7 @@ function admin_rooms() {
           ]),
           sprintf(_("Do you want to delete room %s?"), $name),
           buttons([
-              button(page_link_to('admin_rooms') . '&show=delete&id=' . $id . '&ack', _("Delete"), 'delete') 
+              button(page_link_to('admin_rooms') . '&show=delete&id=' . $room_id . '&ack', _("Delete"), 'delete') 
           ]) 
       ]);
     }
diff --git a/includes/pages/admin_user.php b/includes/pages/admin_user.php
index fb3283bd..56987e12 100644
--- a/includes/pages/admin_user.php
+++ b/includes/pages/admin_user.php
@@ -13,9 +13,9 @@ function admin_user() {
     redirect(users_link());
   }
   
-  $id = $_REQUEST['id'];
+  $user_id = $_REQUEST['id'];
   if (! isset($_REQUEST['action'])) {
-    $user_source = User($id);
+    $user_source = User($user_id);
     if ($user_source === false) {
       engelsystem_error('Unable to load user.');
     }
@@ -26,7 +26,7 @@ function admin_user() {
     
     $html .= "Hallo,<br />" . "hier kannst du den Eintrag &auml;ndern. Unter dem Punkt 'Gekommen' " . "wird der Engel als anwesend markiert, ein Ja bei Aktiv bedeutet, " . "dass der Engel aktiv war und damit ein Anspruch auf ein T-Shirt hat. " . "Wenn T-Shirt ein 'Ja' enth&auml;lt, bedeutet dies, dass der Engel " . "bereits sein T-Shirt erhalten hat.<br /><br />\n";
     
-    $html .= "<form action=\"" . page_link_to("admin_user") . "&action=save&id=$id\" method=\"post\">\n";
+    $html .= "<form action=\"" . page_link_to("admin_user") . "&action=save&id=$user_id\" method=\"post\">\n";
     $html .= "<table border=\"0\">\n";
     $html .= "<input type=\"hidden\" name=\"Type\" value=\"Normal\">\n";
     $html .= "<tr><td>\n";
@@ -80,7 +80,7 @@ function admin_user() {
     
     $html .= form_info('', _('Please visit the angeltypes page or the users profile to manage users angeltypes.'));
     
-    $html .= "Hier kannst Du das Passwort dieses Engels neu setzen:<form action=\"" . page_link_to("admin_user") . "&action=change_pw&id=$id\" method=\"post\">\n";
+    $html .= "Hier kannst Du das Passwort dieses Engels neu setzen:<form action=\"" . page_link_to("admin_user") . "&action=change_pw&id=$user_id\" method=\"post\">\n";
     $html .= "<table>\n";
     $html .= "  <tr><td>Passwort</td><td>" . "<input type=\"password\" size=\"40\" name=\"new_pw\" value=\"\"></td></tr>\n";
     $html .= "  <tr><td>Wiederholung</td><td>" . "<input type=\"password\" size=\"40\" name=\"new_pw2\" value=\"\"></td></tr>\n";
@@ -96,16 +96,16 @@ function admin_user() {
       $my_highest_group = $my_highest_group[0]['group_id'];
     }
     
-    $his_highest_group = sql_select("SELECT * FROM `UserGroups` WHERE `uid`='" . sql_escape($id) . "' ORDER BY `group_id` LIMIT 1");
+    $his_highest_group = sql_select("SELECT * FROM `UserGroups` WHERE `uid`='" . sql_escape($user_id) . "' ORDER BY `group_id` LIMIT 1");
     if (count($his_highest_group) > 0) {
       $his_highest_group = $his_highest_group[0]['group_id'];
     }
     
-    if ($id != $user['UID'] && $my_highest_group <= $his_highest_group) {
-      $html .= "Hier kannst Du die Benutzergruppen des Engels festlegen:<form action=\"" . page_link_to("admin_user") . "&action=save_groups&id=" . $id . "\" method=\"post\">\n";
+    if ($user_id != $user['UID'] && $my_highest_group <= $his_highest_group) {
+      $html .= "Hier kannst Du die Benutzergruppen des Engels festlegen:<form action=\"" . page_link_to("admin_user") . "&action=save_groups&id=" . $user_id . "\" method=\"post\">\n";
       $html .= '<table>';
       
-      $groups = sql_select("SELECT * FROM `Groups` LEFT OUTER JOIN `UserGroups` ON (`UserGroups`.`group_id` = `Groups`.`UID` AND `UserGroups`.`uid` = '" . sql_escape($id) . "') WHERE `Groups`.`UID` >= '" . sql_escape($my_highest_group) . "' ORDER BY `Groups`.`Name`");
+      $groups = sql_select("SELECT * FROM `Groups` LEFT OUTER JOIN `UserGroups` ON (`UserGroups`.`group_id` = `Groups`.`UID` AND `UserGroups`.`uid` = '" . sql_escape($user_id) . "') WHERE `Groups`.`UID` >= '" . sql_escape($my_highest_group) . "' ORDER BY `Groups`.`Name`");
       foreach ($groups as $group) {
         $html .= '<tr><td><input type="checkbox" name="groups[]" value="' . $group['UID'] . '"' . ($group['group_id'] != "" ? ' checked="checked"' : '') . ' /></td><td>' . $group['Name'] . '</td></tr>';
       }
@@ -126,12 +126,12 @@ function admin_user() {
   } else {
     switch ($_REQUEST['action']) {
       case 'save_groups':
-        if ($id != $user['UID']) {
+        if ($user_id != $user['UID']) {
           $my_highest_group = sql_select("SELECT * FROM `UserGroups` WHERE `uid`='" . sql_escape($user['UID']) . "' ORDER BY `group_id`");
-          $his_highest_group = sql_select("SELECT * FROM `UserGroups` WHERE `uid`='" . sql_escape($id) . "' ORDER BY `group_id`");
+          $his_highest_group = sql_select("SELECT * FROM `UserGroups` WHERE `uid`='" . sql_escape($user_id) . "' ORDER BY `group_id`");
           
           if (count($my_highest_group) > 0 && (count($his_highest_group) == 0 || ($my_highest_group[0]['group_id'] <= $his_highest_group[0]['group_id']))) {
-            $groups_source = sql_select("SELECT * FROM `Groups` LEFT OUTER JOIN `UserGroups` ON (`UserGroups`.`group_id` = `Groups`.`UID` AND `UserGroups`.`uid` = '" . sql_escape($id) . "') WHERE `Groups`.`UID` >= '" . sql_escape($my_highest_group[0]['group_id']) . "' ORDER BY `Groups`.`Name`");
+            $groups_source = sql_select("SELECT * FROM `Groups` LEFT OUTER JOIN `UserGroups` ON (`UserGroups`.`group_id` = `Groups`.`UID` AND `UserGroups`.`uid` = '" . sql_escape($user_id) . "') WHERE `Groups`.`UID` >= '" . sql_escape($my_highest_group[0]['group_id']) . "' ORDER BY `Groups`.`Name`");
             $groups = [];
             $grouplist = [];
             foreach ($groups_source as $group) {
@@ -143,15 +143,15 @@ function admin_user() {
               $_REQUEST['groups'] = [];
             }
             
-            sql_query("DELETE FROM `UserGroups` WHERE `uid`='" . sql_escape($id) . "'");
+            sql_query("DELETE FROM `UserGroups` WHERE `uid`='" . sql_escape($user_id) . "'");
             $user_groups_info = [];
             foreach ($_REQUEST['groups'] as $group) {
               if (in_array($group, $grouplist)) {
-                sql_query("INSERT INTO `UserGroups` SET `uid`='" . sql_escape($id) . "', `group_id`='" . sql_escape($group) . "'");
+                sql_query("INSERT INTO `UserGroups` SET `uid`='" . sql_escape($user_id) . "', `group_id`='" . sql_escape($group) . "'");
                 $user_groups_info[] = $groups[$group]['Name'];
               }
             }
-            $user_source = User($id);
+            $user_source = User($user_id);
             engelsystem_log("Set groups of " . User_Nick_render($user_source) . " to: " . join(", ", $user_groups_info));
             $html .= success("Benutzergruppen gespeichert.", true);
           } else {
@@ -184,7 +184,7 @@ function admin_user() {
               `force_active`= " . sql_escape($force_active) . ", 
               `Tshirt` = '" . sql_escape($_POST["eTshirt"]) . "', 
               `Hometown` = '" . sql_escape($_POST["Hometown"]) . "' 
-              WHERE `UID` = '" . sql_escape($id) . "' 
+              WHERE `UID` = '" . sql_escape($user_id) . "' 
               LIMIT 1";
         sql_query($SQL);
         engelsystem_log("Updated user: " . $_POST["eNick"] . ", " . $_POST["eSize"] . ", arrived: " . $_POST["eGekommen"] . ", active: " . $_POST["eAktiv"] . ", tshirt: " . $_POST["eTshirt"]);
@@ -193,8 +193,8 @@ function admin_user() {
       
       case 'change_pw':
         if ($_REQUEST['new_pw'] != "" && $_REQUEST['new_pw'] == $_REQUEST['new_pw2']) {
-          set_password($id, $_REQUEST['new_pw']);
-          $user_source = User($id);
+          set_password($user_id, $_REQUEST['new_pw']);
+          $user_source = User($user_id);
           engelsystem_log("Set new password for " . User_Nick_render($user_source));
           $html .= success("Passwort neu gesetzt.", true);
         } else {
diff --git a/includes/pages/user_messages.php b/includes/pages/user_messages.php
index a3d17741..4af2a0cb 100644
--- a/includes/pages/user_messages.php
+++ b/includes/pages/user_messages.php
@@ -91,14 +91,14 @@ function user_messages() {
     switch ($_REQUEST['action']) {
       case "read":
         if (isset($_REQUEST['id']) && preg_match("/^[0-9]{1,11}$/", $_REQUEST['id'])) {
-          $id = $_REQUEST['id'];
+          $message_id = $_REQUEST['id'];
         } else {
           return error(_("Incomplete call, missing Message ID."), true);
         }
         
-        $message = sql_select("SELECT * FROM `Messages` WHERE `id`='" . sql_escape($id) . "' LIMIT 1");
+        $message = sql_select("SELECT * FROM `Messages` WHERE `id`='" . sql_escape($message_id) . "' LIMIT 1");
         if (count($message) > 0 && $message[0]['RUID'] == $user['UID']) {
-          sql_query("UPDATE `Messages` SET `isRead`='Y' WHERE `id`='" . sql_escape($id) . "' LIMIT 1");
+          sql_query("UPDATE `Messages` SET `isRead`='Y' WHERE `id`='" . sql_escape($message_id) . "' LIMIT 1");
           redirect(page_link_to("user_messages"));
         } else {
           return error(_("No Message found."), true);
@@ -107,14 +107,14 @@ function user_messages() {
       
       case "delete":
         if (isset($_REQUEST['id']) && preg_match("/^[0-9]{1,11}$/", $_REQUEST['id'])) {
-          $id = $_REQUEST['id'];
+          $message_id = $_REQUEST['id'];
         } else {
           return error(_("Incomplete call, missing Message ID."), true);
         }
         
-        $message = sql_select("SELECT * FROM `Messages` WHERE `id`='" . sql_escape($id) . "' LIMIT 1");
+        $message = sql_select("SELECT * FROM `Messages` WHERE `id`='" . sql_escape($message_id) . "' LIMIT 1");
         if (count($message) > 0 && $message[0]['SUID'] == $user['UID']) {
-          sql_query("DELETE FROM `Messages` WHERE `id`='" . sql_escape($id) . "' LIMIT 1");
+          sql_query("DELETE FROM `Messages` WHERE `id`='" . sql_escape($message_id) . "' LIMIT 1");
           redirect(page_link_to("user_messages"));
         } else {
           return error(_("No Message found."), true);
diff --git a/includes/pages/user_myshifts.php b/includes/pages/user_myshifts.php
index f50711a7..b60d2ed8 100644
--- a/includes/pages/user_myshifts.php
+++ b/includes/pages/user_myshifts.php
@@ -10,12 +10,12 @@ function user_myshifts() {
   global $user, $privileges;
   
   if (isset($_REQUEST['id']) && in_array("user_shifts_admin", $privileges) && preg_match("/^[0-9]{1,}$/", $_REQUEST['id']) && sql_num_query("SELECT * FROM `User` WHERE `UID`='" . sql_escape($_REQUEST['id']) . "'") > 0) {
-    $id = $_REQUEST['id'];
+    $user_id = $_REQUEST['id'];
   } else {
-    $id = $user['UID'];
+    $user_id = $user['UID'];
   }
   
-  list($shifts_user) = sql_select("SELECT * FROM `User` WHERE `UID`='" . sql_escape($id) . "' LIMIT 1");
+  list($shifts_user) = sql_select("SELECT * FROM `User` WHERE `UID`='" . sql_escape($user_id) . "' LIMIT 1");
   
   if (isset($_REQUEST['reset'])) {
     if ($_REQUEST['reset'] == "ack") {
@@ -28,7 +28,7 @@ function user_myshifts() {
         button(page_link_to('user_myshifts') . '&reset=ack', _("Continue"), 'btn-danger') 
     ]);
   } elseif (isset($_REQUEST['edit']) && preg_match("/^[0-9]*$/", $_REQUEST['edit'])) {
-    $id = $_REQUEST['edit'];
+    $user_id = $_REQUEST['edit'];
     $shift = sql_select("SELECT
         `ShiftEntry`.`freeloaded`,
         `ShiftEntry`.`freeload_comment`,
@@ -43,7 +43,7 @@ function user_myshifts() {
         JOIN `Shifts` ON (`ShiftEntry`.`SID` = `Shifts`.`SID`)
         JOIN `ShiftTypes` ON (`ShiftTypes`.`id` = `Shifts`.`shifttype_id`)
         JOIN `Room` ON (`Shifts`.`RID` = `Room`.`RID`)
-        WHERE `ShiftEntry`.`id`='" . sql_escape($id) . "'
+        WHERE `ShiftEntry`.`id`='" . sql_escape($user_id) . "'
         AND `UID`='" . sql_escape($shifts_user['UID']) . "' LIMIT 1");
     if (count($shift) > 0) {
       $shift = $shift[0];
@@ -66,7 +66,7 @@ function user_myshifts() {
         
         if ($valid) {
           $result = ShiftEntry_update([
-              'id' => $id,
+              'id' => $user_id,
               'Comment' => $comment,
               'freeloaded' => $freeloaded,
               'freeload_comment' => $freeload_comment 
@@ -85,16 +85,16 @@ function user_myshifts() {
     } else
       redirect(page_link_to('user_myshifts'));
   } elseif (isset($_REQUEST['cancel']) && preg_match("/^[0-9]*$/", $_REQUEST['cancel'])) {
-    $id = $_REQUEST['cancel'];
+    $user_id = $_REQUEST['cancel'];
     $shift = sql_select("
         SELECT *
         FROM `Shifts` 
         INNER JOIN `ShiftEntry` USING (`SID`) 
-        WHERE `ShiftEntry`.`id`='" . sql_escape($id) . "' AND `UID`='" . sql_escape($shifts_user['UID']) . "'");
+        WHERE `ShiftEntry`.`id`='" . sql_escape($user_id) . "' AND `UID`='" . sql_escape($shifts_user['UID']) . "'");
     if (count($shift) > 0) {
       $shift = $shift[0];
       if (($shift['start'] > time() + $LETZTES_AUSTRAGEN * 3600) || in_array('user_shifts_admin', $privileges)) {
-        $result = ShiftEntry_delete($id);
+        $result = ShiftEntry_delete($user_id);
         if ($result === false) {
           engelsystem_error('Unable to delete shift entry.');
         }
diff --git a/includes/pages/user_questions.php b/includes/pages/user_questions.php
index 6d9ded8e..10e8fef6 100644
--- a/includes/pages/user_questions.php
+++ b/includes/pages/user_questions.php
@@ -39,14 +39,14 @@ function user_questions() {
         break;
       case 'delete':
         if (isset($_REQUEST['id']) && preg_match("/^[0-9]{1,11}$/", $_REQUEST['id'])) {
-          $id = $_REQUEST['id'];
+          $question_id = $_REQUEST['id'];
         } else {
           return error(_("Incomplete call, missing Question ID."), true);
         }
         
-        $question = sql_select("SELECT * FROM `Questions` WHERE `QID`='" . sql_escape($id) . "' LIMIT 1");
+        $question = sql_select("SELECT * FROM `Questions` WHERE `QID`='" . sql_escape($question_id) . "' LIMIT 1");
         if (count($question) > 0 && $question[0]['UID'] == $user['UID']) {
-          sql_query("DELETE FROM `Questions` WHERE `QID`='" . sql_escape($id) . "' LIMIT 1");
+          sql_query("DELETE FROM `Questions` WHERE `QID`='" . sql_escape($question_id) . "' LIMIT 1");
           redirect(page_link_to("user_questions"));
         } else {
           return page_with_title(questions_title(), [
diff --git a/includes/sys_template.php b/includes/sys_template.php
index 23f4b77b..43ca66f2 100644
--- a/includes/sys_template.php
+++ b/includes/sys_template.php
@@ -41,9 +41,9 @@ function glyph_bool($boolean) {
   return '<span class="text-' . ($boolean ? 'success' : 'danger') . '">' . glyph($boolean ? 'ok' : 'remove') . '</span>';
 }
 
-function div($class, $content = array(), $id = "") {
-  $id = $id != '' ? ' id="' . $id . '"' : '';
-  return '<div' . $id . ' class="' . $class . '">' . join("\n", $content) . '</div>';
+function div($class, $content = array(), $dom_id = "") {
+  $dom_id = $dom_id != '' ? ' id="' . $dom_id . '"' : '';
+  return '<div' . $dom_id . ' class="' . $class . '">' . join("\n", $content) . '</div>';
 }
 
 function heading($content, $number = 1) {
@@ -84,12 +84,12 @@ function toolbar_dropdown($glyphicon, $label, $submenu, $class = '') {
 }
 
 function toolbar_popover($glyphicon, $label, $content, $class = '') {
-  $id = md5(microtime() . $glyphicon . $label);
+  $dom_id = md5(microtime() . $glyphicon . $label);
   return '<li class="dropdown messages ' . $class . '">
-          <a id="' . $id . '" href="#" tabindex="0">' . ($glyphicon != '' ? '<span class="glyphicon glyphicon-' . $glyphicon . '"></span> ' : '') . $label . ' <span class="caret"></span></a>
+          <a id="' . $dom_id . '" href="#" tabindex="0">' . ($glyphicon != '' ? '<span class="glyphicon glyphicon-' . $glyphicon . '"></span> ' : '') . $label . ' <span class="caret"></span></a>
           <script type="text/javascript">
           $(function(){
-              $("#' . $id . '").popover({
+              $("#' . $dom_id . '").popover({
                   trigger: "focus", 
                   html: true, 
                   content: "' . addslashes(join('', $content)) . '", 
@@ -145,16 +145,16 @@ function form_spinner($name, $label, $value) {
  * @return HTML
  */
 function form_date($name, $label, $value, $start_date = '') {
-  $id = $name . '-date';
+  $dom_id = $name . '-date';
   $value = is_numeric($value) ? date('Y-m-d', $value) : '';
   $start_date = is_numeric($start_date) ? date('Y-m-d', $start_date) : '';
   return form_element($label, '
-    <div class="input-group date" id="' . $id . '">
+    <div class="input-group date" id="' . $dom_id . '">
       <input type="text" name="' . $name . '" class="form-control" value="' . $value . '"><span class="input-group-addon">' . glyph('th') . '</span>
     </div>
     <script type="text/javascript">
 			$(function(){
-        $("#' . $id . '").datepicker({
+        $("#' . $dom_id . '").datepicker({
 				  language: "' . locale_short() . '",
           todayBtn: "linked",
           format: "yyyy-mm-dd",
@@ -162,7 +162,7 @@ function form_date($name, $label, $value, $start_date = '') {
 			  });
       });  
     </script>
-    ', $id);
+    ', $dom_id);
 }
 
 /**
@@ -208,14 +208,14 @@ function form_multi_checkboxes($names, $label, $items, $selected, $disabled = ar
   foreach ($items as $key => $item) {
     $html .= "<tr>";
     foreach ($names as $name => $title) {
-      $id = $name . '_' . $key;
+      $dom_id = $name . '_' . $key;
       $sel = array_search($key, $selected[$name]) !== false ? ' checked="checked"' : "";
       if (! empty($disabled) && ! empty($disabled[$name]) && array_search($key, $disabled[$name]) !== false) {
         $sel .= ' disabled="disabled"';
       }
-      $html .= '<td style="text-align: center;"><input type="checkbox" id="' . $id . '" name="' . $name . '[]" value="' . $key . '"' . $sel . ' /></td>';
+      $html .= '<td style="text-align: center;"><input type="checkbox" id="' . $dom_id . '" name="' . $name . '[]" value="' . $key . '"' . $sel . ' /></td>';
     }
-    $html .= '<td><label for="' . $id . '">' . $item . '</label></td></tr>';
+    $html .= '<td><label for="' . $dom_id . '">' . $item . '</label></td></tr>';
   }
   $html .= "</tbody></table>";
   return form_element($label, $html);
@@ -452,8 +452,8 @@ function html_options($name, $options, $selected = "") {
   return $html;
 }
 
-function html_select_key($id, $name, $rows, $selected) {
-  $html = '<select class="form-control" id="' . $id . '" name="' . $name . '">';
+function html_select_key($dom_id, $name, $rows, $selected) {
+  $html = '<select class="form-control" id="' . $dom_id . '" name="' . $name . '">';
   foreach ($rows as $key => $row) {
     if (($key == $selected) || ($row == $selected)) {
       $html .= '<option value="' . $key . '" selected="selected">' . $row . '</option>';
diff --git a/public/index.php b/public/index.php
index 51c8e7eb..996c2b77 100644
--- a/public/index.php
+++ b/public/index.php
@@ -19,126 +19,126 @@ $free_pages = [
 ];
 
 // Gewünschte Seite/Funktion
-$p = "";
+$page = "";
 if (! isset($_REQUEST['p'])) {
   $_REQUEST['p'] = isset($user) ? "news" : "login";
 }
 
 if (isset($_REQUEST['p']) && preg_match("/^[a-z0-9_]*$/i", $_REQUEST['p']) && (in_array($_REQUEST['p'], $free_pages) || in_array($_REQUEST['p'], $privileges))) {
-  $p = $_REQUEST['p'];
+  $page = $_REQUEST['p'];
   
-  $title = $p;
+  $title = $page;
   $content = "";
   
-  if ($p == "api") {
+  if ($page == "api") {
     require_once realpath(__DIR__ . '/../includes/controller/api.php');
     error("Api disabled temporily.");
     redirect(page_link_to('login'));
     api_controller();
-  } elseif ($p == "ical") {
+  } elseif ($page == "ical") {
     require_once realpath(__DIR__ . '/../includes/pages/user_ical.php');
     user_ical();
-  } elseif ($p == "atom") {
+  } elseif ($page == "atom") {
     require_once realpath(__DIR__ . '/../includes/pages/user_atom.php');
     user_atom();
-  } elseif ($p == "shifts_json_export") {
+  } elseif ($page == "shifts_json_export") {
     require_once realpath(__DIR__ . '/../includes/controller/shifts_controller.php');
     shifts_json_export_controller();
-  } elseif ($p == "shifts_json_export_all") {
+  } elseif ($page == "shifts_json_export_all") {
     require_once realpath(__DIR__ . '/../includes/controller/shifts_controller.php');
     shifts_json_export_all_controller();
-  } elseif ($p == "stats") {
+  } elseif ($page == "stats") {
     require_once realpath(__DIR__ . '/../includes/pages/guest_stats.php');
     guest_stats();
-  } elseif ($p == "user_password_recovery") {
+  } elseif ($page == "user_password_recovery") {
     require_once realpath(__DIR__ . '/../includes/controller/users_controller.php');
     $title = user_password_recovery_title();
     $content = user_password_recovery_controller();
-  } elseif ($p == "angeltypes") {
+  } elseif ($page == "angeltypes") {
     list($title, $content) = angeltypes_controller();
-  } elseif ($p == "shifts") {
+  } elseif ($page == "shifts") {
     list($title, $content) = shifts_controller();
-  } elseif ($p == "users") {
+  } elseif ($page == "users") {
     list($title, $content) = users_controller();
-  } elseif ($p == "user_angeltypes") {
+  } elseif ($page == "user_angeltypes") {
     list($title, $content) = user_angeltypes_controller();
-  } elseif ($p == "user_driver_licenses") {
+  } elseif ($page == "user_driver_licenses") {
     list($title, $content) = user_driver_licenses_controller();
-  } elseif ($p == "shifttypes") {
+  } elseif ($page == "shifttypes") {
     list($title, $content) = shifttypes_controller();
-  } elseif ($p == "admin_event_config") {
+  } elseif ($page == "admin_event_config") {
     list($title, $content) = event_config_edit_controller();
-  } elseif ($p == "news") {
+  } elseif ($page == "news") {
     $title = news_title();
     $content = user_news();
-  } elseif ($p == "news_comments") {
+  } elseif ($page == "news_comments") {
     require_once realpath(__DIR__ . '/../includes/pages/user_news.php');
     $title = user_news_comments_title();
     $content = user_news_comments();
-  } elseif ($p == "user_meetings") {
+  } elseif ($page == "user_meetings") {
     $title = meetings_title();
     $content = user_meetings();
-  } elseif ($p == "user_myshifts") {
+  } elseif ($page == "user_myshifts") {
     $title = myshifts_title();
     $content = user_myshifts();
-  } elseif ($p == "user_shifts") {
+  } elseif ($page == "user_shifts") {
     $title = shifts_title();
     $content = user_shifts();
-  } elseif ($p == "user_messages") {
+  } elseif ($page == "user_messages") {
     $title = messages_title();
     $content = user_messages();
-  } elseif ($p == "user_questions") {
+  } elseif ($page == "user_questions") {
     $title = questions_title();
     $content = user_questions();
-  } elseif ($p == "user_settings") {
+  } elseif ($page == "user_settings") {
     $title = settings_title();
     $content = user_settings();
-  } elseif ($p == "login") {
+  } elseif ($page == "login") {
     $title = login_title();
     $content = guest_login();
-  } elseif ($p == "register") {
+  } elseif ($page == "register") {
     $title = register_title();
     $content = guest_register();
-  } elseif ($p == "logout") {
+  } elseif ($page == "logout") {
     $title = logout_title();
     $content = guest_logout();
-  } elseif ($p == "admin_questions") {
+  } elseif ($page == "admin_questions") {
     $title = admin_questions_title();
     $content = admin_questions();
-  } elseif ($p == "admin_user") {
+  } elseif ($page == "admin_user") {
     $title = admin_user_title();
     $content = admin_user();
-  } elseif ($p == "admin_arrive") {
+  } elseif ($page == "admin_arrive") {
     $title = admin_arrive_title();
     $content = admin_arrive();
-  } elseif ($p == "admin_active") {
+  } elseif ($page == "admin_active") {
     $title = admin_active_title();
     $content = admin_active();
-  } elseif ($p == "admin_free") {
+  } elseif ($page == "admin_free") {
     $title = admin_free_title();
     $content = admin_free();
-  } elseif ($p == "admin_news") {
+  } elseif ($page == "admin_news") {
     require_once realpath(__DIR__ . '/../includes/pages/admin_news.php');
     $content = admin_news();
-  } elseif ($p == "admin_rooms") {
+  } elseif ($page == "admin_rooms") {
     $title = admin_rooms_title();
     $content = admin_rooms();
-  } elseif ($p == "admin_groups") {
+  } elseif ($page == "admin_groups") {
     $title = admin_groups_title();
     $content = admin_groups();
-  } elseif ($p == "admin_language") {
+  } elseif ($page == "admin_language") {
     require_once realpath(__DIR__ . '/../includes/pages/admin_language.php');
     $content = admin_language();
-  } elseif ($p == "admin_import") {
+  } elseif ($page == "admin_import") {
     $title = admin_import_title();
     $content = admin_import();
-  } elseif ($p == "admin_shifts") {
+  } elseif ($page == "admin_shifts") {
     $title = admin_shifts_title();
     $content = admin_shifts();
-  } elseif ($p == "admin_log") {
+  } elseif ($page == "admin_log") {
     $title = admin_log_title();
     $content = admin_log();
-  } elseif ($p == "credits") {
+  } elseif ($page == "credits") {
     require_once realpath(__DIR__ . '/../includes/pages/guest_credits.php');
     $title = credits_title();
     $content = guest_credits();
@@ -165,7 +165,7 @@ if ($event_config === false) {
 echo template_render('../templates/layout.html', [
     'theme' => isset($user) ? $user['color'] : $default_theme,
     'title' => $title,
-    'atom_link' => ($p == 'news' || $p == 'user_meetings') ? '<link href="' . page_link_to('atom') . (($p == 'user_meetings') ? '&amp;meetings=1' : '') . '&amp;key=' . $user['api_key'] . '" type="application/atom+xml" rel="alternate" title="Atom Feed">' : '',
+    'atom_link' => ($page == 'news' || $page == 'user_meetings') ? '<link href="' . page_link_to('atom') . (($page == 'user_meetings') ? '&amp;meetings=1' : '') . '&amp;key=' . $user['api_key'] . '" type="application/atom+xml" rel="alternate" title="Atom Feed">' : '',
     'menu' => make_menu(),
     'content' => msg() . $content,
     'header_toolbar' => header_toolbar(),