function datetime_ntp_enable_change(f)
{
	var f=document.dtform;
	if (f.datetime_ntp_enable[0].checked) {		// ntp disabled
		id_visible("row_dst_enable");
		id_invisible("row_ntp_updateinterval");
		id_invisible("row_ntp_server1");
		id_invisible("row_ntp_server2");
		id_visible("row_date");
		id_visible("row_time");

	} else if (f.datetime_ntp_enable[1].checked) {	// ntp enabled
		id_visible("row_dst_enable");
		id_visible("row_ntp_updateinterval");
		id_visible("row_ntp_server1");
		id_visible("row_ntp_server2");
		id_invisible("row_date");
		id_invisible("row_time");
	}
}

function submitchk(f)
{
	if (f.datetime_ntp_enable.value=="1"){
		if (!integer_between(f.datetime_ntp_updateinterval.value, 1, 1000, "NTP Update Interval should be an integer between 1..1000.") ||
			!valid(f.datetime_ntp_server1.value, is_hostname, "NTP server1 is in invalid format.") ||
			!valid_or_null(f.datetime_ntp_server2.value, is_hostname, "NTP server2 is in invalid format.") ) {
			return false;
		}
	}
	return true;
}