protected function _getOverrides($format, $parameters = array())
    {
        $overrides = array();

        if (!empty($parameters))
        {
            // Get the power set of the set of parameters and construct a list of string overrides from it.
            foreach ($this->_getPowerSet(array_keys($parameters)) as $subset)
            {
                $override = $format;

                foreach ($subset as $key) {
                    $override = str_replace(sprintf('{%s}', $key), $parameters[$key], $override);
                }

                $overrides[] = $override;
            }
        }

        return $overrides;
    }