Horde_Icalendar::_exportDuration PHP Метод

    protected function _exportDuration($value)
    {
        $duration = '';
        if ($value < 0) {
            $value *= -1;
            $duration .= '-';
        }
        $duration .= 'P';
        $weeks = floor($value / (7 * 86400));
        $value = $value % (7 * 86400);
        if ($weeks) {
            $duration .= $weeks . 'W';
        }
        $days = floor($value / 86400);
        $value = $value % 86400;
        if ($days) {
            $duration .= $days . 'D';
        }
        if ($value) {
            $duration .= 'T';
            $hours = floor($value / 3600);
            $value = $value % 3600;
            if ($hours) {
                $duration .= $hours . 'H';
            }
            $mins = floor($value / 60);
            $value = $value % 60;
            if ($mins) {
                $duration .= $mins . 'M';
            }
            if ($value) {
                $duration .= $value . 'S';
            }
        } elseif ($duration === 'P') {
            // Duration without time ("P") is NOT valid, append 0 seconds
            // ("T0S").
            $duration .= 'T0S';
        }
        return $duration;
    }