function flushStacked_abbr() {
    $out = array();
    foreach ($this->stack['abbr'] as $k => $tag) {
      if (!isset($tag['unstacked'])) {
        array_push($out, ' *['.$tag['text'].']: '.$tag['title']);
        $tag['unstacked'] = true;
        $this->stack['abbr'][$k] = $tag;
      }
    }
    if (!empty($out)) {
      $this->out("\n\n".implode("\n", $out));
    }
  }