for ($m = 0; $m < 60; $m += 5) {
                if ($m == $start_min) {
                    $select_start_min .= "<option value='$m' selected>" . sprintf('%02d', $m) . "</option>\n";
                } else {
                    $select_start_min .= "<option value='$m'>" . sprintf('%02d', $m) . "</option>\n";