public function getRules()
{
return array('ml' => array('symbol' => 'mL', 'rate' => 0.001), 'cm3' => array('symbol' => 'cm3', 'rate' => 0.1), 'm3' => array('symbol' => 'm3', 'rate' => 1000), 'lit' => array('symbol' => 'L', 'rate' => 1), 'qt' => array('symbol' => 'US quart', 'rate' => 0.946352946), 'pt' => array('symbol' => 'US pint', 'rate' => 0.5682612500000001), 'gal' => array('symbol' => 'US gallon', 'rate' => 3.785411784), 'bbl' => array('symbol' => 'Barrel', 'rate' => 119.240471196));
}