public function getRules()
{
return array('mm2' => array('symbol' => 'mm2', 'rate' => 1.0E-6), 'cm2' => array('symbol' => 'cm2', 'rate' => 0.0001), 'm2' => array('symbol' => 'm2', 'rate' => 1), 'km2' => array('symbol' => 'km2', 'rate' => 1000000), 'ft2' => array('symbol' => 'sq ft', 'rate' => 0.09290341000000001), 'ch2' => array('symbol' => 'sq ch', 'rate' => 404.6873), 'acr' => array('symbol' => 'Acre', 'rate' => 4046.873), 'ar' => array('symbol' => 'Ar', 'rate' => 100), 'ga' => array('symbol' => 'Ga', 'rate' => 10000));
}