diff --git a/filters.inc.php b/filters.inc.php
index 73c6d7b..b0f9cdb 100644
--- a/filters.inc.php
+++ b/filters.inc.php
@@ -4,6 +4,10 @@ use Exception;
 
 function flt_str2num($val, $name, $struct, $args)
 {
+  $config_extra = $GLOBALS['CONFIG_EXTRAS'];
+  if(!property_exists($config_extra, 'flt_str2num_entries'))
+    $config_extra->flt_str2num_entries = array();
+
   if(is_string($val))
   {
     if(strlen($val) === 0)
@@ -30,9 +34,27 @@ function flt_str2num($val, $name, $struct, $args)
   if(!is_numeric($val))
     throw new Exception("Bad value, not a number(" . serialize($val) . ")");
 
+  $config_extra->flt_str2num_entries[1*$val] = true;
+
   return 1*$val;
 }
 
+function validate_flt_str2num(\taskman\ConfigFetchResult $fetch_result, \taskman\ConfigCacheEntry $entry)
+{
+  $config_extra = $entry->extras;
+
+  if(!property_exists($config_extra, 'flt_str2num_entries'))
+    return;
+
+  foreach($config_extra->flt_str2num_entries as $conf_id => $_) 
+  {
+    if($conf_id == 0)
+      continue;
+
+    \taskman\config_find_by_id($fetch_result, $conf_id);
+  }
+}
+
 function flt_range($val, $name, $struct, $args)
 {
   if(count($args) != 2)
@@ -76,30 +98,65 @@ function flt_time($val, $name, $struct, $args)
 function flt_class($val, $name, $struct, $args)
 {
   global $GAME_ROOT;
-  
-  if(is_string($val))
-  {
-    $conf_path = $val;
-    
-    if(strpos($conf_path, '@') === 0)
-      $conf_path = substr($conf_path, 1) . '.conf.js';
 
-    $conf_path = \taskman\config_real_path($conf_path);
-    
-    $cce = \taskman\config_fetch_by_path($conf_path);
+  $config_extra = $GLOBALS['CONFIG_EXTRAS'];
+  if(!property_exists($config_extra, 'flt_class_entries'))
+    $config_extra->flt_class_entries = array();
 
-    $conf_class = $cce->class;
+  $target_class = $args;
+  if(is_array($target_class))
+    $target_class = $target_class[0];
 
-    $target_class = $args;
-    if(is_array($target_class))
-      $target_class = $target_class[0];
+  if(!class_exists($target_class))
+    throw new Exception($val.". Target class \"".$target_class."\" is not valid");
 
-    if(!class_exists($target_class))
-      throw new Exception($val.". Target class \"".$target_class."\" is not valid");
-    
-    if($conf_class != $target_class && !is_subclass_of($conf_class, $target_class))
-      throw new Exception($val.". Config class is \"".$conf_class."\". Must be \"".$target_class."\" or it's child");
-  }
+  $config_extra->flt_class_entries[$val] = $target_class;
   
   return $val;
 }
+
+function validate_flt_class(\taskman\ConfigFetchResult $fetch_result, \taskman\ConfigCacheEntry $entry)
+{
+  $config_extra = $entry->extras;
+
+  if(!property_exists($config_extra, 'flt_class_entries'))
+    return;
+  
+  foreach($config_extra->flt_class_entries as $conf_ref => $target_class) 
+  {
+    $conf_cache = null;
+
+    if(is_string($conf_ref))
+    {
+      if(empty($conf_ref))
+        continue;
+
+      $conf_path = $conf_ref;
+      
+      if(strpos($conf_path, '@') === 0)
+        $conf_path = substr($conf_path, 1) . '.conf.js';
+
+      $conf_path = \taskman\normalize_path(\taskman\config_real_path($conf_path), true);
+
+      $conf_cache = \taskman\config_find_by_path($fetch_result, $conf_path);
+    }
+    else if(is_int($conf_ref))
+    {
+      if($conf_ref == 0)
+        continue;
+
+      $conf_cache = \taskman\config_find_by_id($fetch_result, $conf_ref);
+    }
+    else
+      throw new Exception("Invalid config ref: '$conf_ref'");
+
+    if($conf_cache == null)
+      throw new Exception("Config not found by ref: '$conf_ref'");
+
+    $conf_class = $conf_cache->class;
+
+    if($conf_class != $target_class && !is_subclass_of($conf_class, $target_class))
+      throw new Exception("Config class is '$conf_class'. Must be '$target_class' or its child");
+  }
+}
+