function exportValue(&$submitValues, $notused = false) {
        // Get the values from all the child elements.
        $valuearray = array();
        foreach ($this->_elements as $element) {
            $thisexport = $element->exportValue($submitValues[$this->getName()], true);
            if (!is_null($thisexport)) {
                $valuearray += $thisexport;
            }
        }

        // Convert the value to an integer number of seconds.
        if (empty($valuearray)) {
            return null;
        }
        if ($this->_options['optional'] && empty($valuearray['enabled'])) {
            return array($this->getName() => 0);
        }
        return array($this->getName() => $valuearray['number'] * $valuearray['timeunit']);
    }