timezone_bs.php

<?php
$tz = array(
    'Europe/Paris'
    ,'America/New_York'
);
$dates = array(
    array('2014-02-01', '2014-03-01'),
    array('2014-06-01', '2014-07-01'),
);
foreach($tz as $zone) {
    foreach($dates as $dateTuple) {
        $date1 = new DateTime($dateTuple[0], new DateTimeZone($zone));
        $date2 = new DateTime($dateTuple[1], new DateTimeZone($zone));
        echo $date1->diff($date2)->format('P%yY%mM%dDT%hH%iM%sS') . "\t{$zone}" . PHP_EOL;
        echo $date1->format(DateTime::ISO8601) . PHP_EOL;
        echo $date2->format(DateTime::ISO8601) . PHP_EOL . PHP_EOL;
    }
}
exit(0);