offset.php

<?php
// returns a timezone that is at the given offset
// taking into consideration if the timezone
// is currently observing DST or not.
//
// offset: timezone offset in seconds
function tz_from_offset($offset) {
	$tz = timezone_name_from_abbr(0, $offset, 0);
	$date = date_create("now", new DateTimeZone($tz));
	if ($date->getOffset() != $offset) {
		$tz = timezone_name_from_abbr(0, $offset, 1);
	}
	return $tz;
}
?>