public function DiscussionModel_BeforeSaveDiscussion_Handler($Sender, $Args) {
      $FormPostValues = GetValue('FormPostValues', $Args, array());
      $TagsString = trim(strtolower(GetValue('Tags', $FormPostValues, '')));
      $NumTagsMax = C('Plugin.Tagging.Max', 5);
      // Tags can only contain unicode and the following ASCII: a-z 0-9 + # _ .
      if (StringIsNullOrEmpty($TagsString) && C('Plugins.Tagging.Required')) {
         $Sender->Validation->AddValidationResult('Tags', 'You must specify at least one tag.');
      } else {
         $Tags = TagModel::SplitTags($TagsString);
         if (!TagModel::ValidateTags($Tags)) {
            $Sender->Validation->AddValidationResult('Tags', '@'.T('ValidateTag', 'Tags cannot contain commas.'));
         } elseif (count($Tags) > $NumTagsMax) {
            $Sender->Validation->AddValidationResult('Tags', '@'.sprintf(T('You can only specify up to %s tags.'), $NumTagsMax));
         } else {
            
         }
      }
   }