var	old = false;
var	type = "(unknown browser?)";

var agt = navigator.userAgent.toLowerCase();

var is_major = parseInt(navigator.appVersion);
var is_minor = parseFloat(navigator.appVersion);

if (((agt.indexOf("msie") != -1) && (agt.indexOf("opera") == -1)))
{
	type = "Internet Explorer";

	if (is_major < 4 || agt.indexOf("msie 4") != -1 || agt.indexOf("msie 5.0") != -1)
	{
		old = true;
	}
}
else
if (((agt.indexOf('mozilla') != -1) && (agt.indexOf('spoofer') == -1)
			&& (agt.indexOf('compatible') == -1) && (agt.indexOf('opera') == -1)
			&& (agt.indexOf('webtv')== -1) && (agt.indexOf('hotjava')== -1)))
{
	type = "Netscape";

	if (is_major <= 4)
	{
		old = true;
	}
}
else
if (agt.indexOf("opera") != -1)
{
	type = "Opera";

	if (agt.indexOf("opera 2") != -1 || agt.indexOf("opera/2") != -1 ||
		agt.indexOf("opera 3") != -1 || agt.indexOf("opera/3") != -1 ||
		agt.indexOf("opera 4") != -1 || agt.indexOf("opera/4") != -1 ||
		agt.indexOf("opera 5") != -1 || agt.indexOf("opera/5") != -1 ||
		agt.indexOf("opera 6") != -1 || agt.indexOf("opera/6") != -1)
	{
		old = true;
	}
}

if (old)
{
	document.write ("The MathsNetGCSE web site requires a modern web browser that understands " +
		'<a href="http://www.w3.org/Style/CSS/" target="_blank">CSS<\/a> version 1 and above. ' +
		"Unfortunately, your " + type + " browser is just too old. Please try one of these: " +
		'<a href="http://www.mozilla.org" target="_blank">Mozilla / Firefox<\/a> | ' +
		'<a href="http://channels.netscape.com/ns/browsers/default.jsp" target="_blank">Netscape 7+<\/a> | ' +
		'<a href="http://www.opera.com/" target="_blank">Opera 7+<\/a> | ' +
		'<a href="http://www.microsoft.com/" target="_blank">IE 6+ (PC only)<\/a> | ' +
		'<a href="http://www.apple.com/" target="_blank">Safari (Mac only)<\/a> ');
}