var ms = navigator.appVersion.indexOf("MSIE");
var ie4 = (ms > 0) && (parseInt(navigator.appVersion.substring(ms+5, ms+6)) == 4);
var ns4 = (document.layers) ? true : false;
var ns6 = (document.getElementById && !document.all) ? true : false;
var is6 = (ms > 0 && !ie4) ? true : false;

function switch_ul(lay) {

if (ie4) 
	if (document.all[lay].style.visibility == "hidden")
		{document.all[lay].style.visibility = "visible";}
	else
		{
		document.all[lay].style.visibility = "hidden";
		}

if (ns4) 
	if (document.layers[lay].visibility == "hide")
		{document.layers[lay].visibility = "show";}
	else
		{
		document.layers[lay].visibility = "hide";
		}

if (ns6) 
	if (document.getElementById([lay]).style.display == "none")
		{
		document.getElementById([lay]).style.display = "block";
		}
	else
		{
		document.getElementById([lay]).style.display = "none";
		}

if (is6) 
	if (document.getElementById([lay]).style.display == "none")
		{
		document.getElementById([lay]).style.display = "block";
		}
	else
		{
		document.getElementById([lay]).style.display = "none";
		}
}

function switchAll()
{
         switch_ul("bi1");
         switch_ul("bi2");
         switch_ul("bi3");
         switch_ul("bi4");
         switch_ul("bi5");
         switch_ul("bi6");
}