- strtotime: documentation ( source)
<?php echo "FROM TIMESTAMP, NO TZ:\n";
$date = new DateTime('@'.strtotime('2012-08-22 00:00:00 CEST'));
echo $date->format('Y-m-d H:i:s T').' (offset '.$date->getOffset().")\n";
$date->modify('+0 days');
echo $date->format('Y-m-d H:i:s T').' (offset '.$date->getOffset().")\n"; ?>