public function addFootnote($text, $label = null)
    {
        if (isset($this->_parentConfig))
            return ($this->_parentConfig->addFootnote($text, $label));
        if (is_null($label))
            $this->_footnotes[] = $text;
        else
            $this->_footnotes[] = array(
                'label' => $label,
                'text' => $text
            );
        $index = count($this->_footnotes);
        return (array(
            'id' => $this->getParam('footnotesPrefix') . "-$index",
            'index' => $index
        ));
    }