function fkManufacturerChanged() {
	$('Model').selectedIndex = 0;
	$('Model').disabled = true;
	var man = $('fkManufacturer').value;
	if (man == '') {
		$('fkSeries').selectedIndex = 0;
		$('fkSeries').disabled = true;
	} else {
		var i = 0;
		var key;
		$('fkSeries').options.length = 1;
		$('fkSeries').disabled = false;
		var series = ms[man];
		for (key in series) {
			i++;
			$('fkSeries').options[i] = new Option(sr[series[key]],series[key],false,false);
		}
	}
}

function fkSeriesChanged() {
	var series = $('fkSeries').value;
	if (series != '') {
		var i = 0;
		var key;
		$('Model').options.length = 1;
		$('Model').disabled = false;
		if (ds[series]) {
			var model = ds[series];
			for (key in model) {
				i++;
				$('Model').options[i] = new Option(md[model[key]],model[key],false,false);
			}
			return true;
		}
	}
	$('Model').selectedIndex = 0;
	$('Model').disabled = true;
}