function __construct()
{
$this->valid_components = array();
$this->valid_properties = array('DTSTART' => RFC2445_REQUIRED | RFC2445_ONCE, 'TZOFFSETTO' => RFC2445_REQUIRED | RFC2445_ONCE, 'TZOFFSETFROM' => RFC2445_REQUIRED | RFC2445_ONCE, 'COMMENT' => RFC2445_OPTIONAL, 'RDATE' => RFC2445_OPTIONAL, 'RRULE' => RFC2445_OPTIONAL, 'TZNAME' => RFC2445_OPTIONAL, RFC2445_XNAME => RFC2445_OPTIONAL);
parent::__construct();
}
