public function save($data, $form) {
		//look for attendee id in form field or request params
		$attendeeid = $form->Fields()->fieldByName("ID")->dataValue();
		//look for existing attendee
		$attendee = $this->registration->Attendees()
			->byID((int)$attendeeid);
		//prevent changes to the type of ticket
		if($attendee && $attendee->TicketID && $attendee->TicketID != $data['TicketID']){
			$form->sessionMessage('You cannot change the ticket', 'bad');
			return $this->redirectBack();
		}
		//create new attendee
		if(!$attendee){
			$attendee = $this->createAttendee();
		}
		//save ticket selection
		$form->saveInto($attendee);
		$attendee->write();

		$this->registration->calculateTotal();
		$this->registration->write();

		$this->extend("onSave", $attendee, $this->registration);
		
		return $this->redirect($this->NextURL);
	}