function updatetag($start, $end, $text, $data) {
	$pos1 = strpos($text, $start); 
	if(!is_integer($pos1)) {
		$res = $text.$start.$data.$end;
		return $res;
	} 
	$pos1 += strlen($start); 
	$pos2 = strpos($text, $end, $pos1); 
	if(!is_integer($pos2)) {
		$pos = false;
		return false;
	} 
	$t1 = substr($text, 0, $pos1);
	$t2 = substr($text, $pos2);
	$res = $t1.$data.$t2;

	return $res;
}