var ie4 = (document.all) ? true : false;
var ns4 = (document.layers) ? true : false;
var ns6 = (document.getElementById && !document.all) ? true : false;

function hidelayer(lay) {
	if (ie4) {document.all[lay].style.visibility = "hidden";}
	if (ns4) {document.layers[lay].visibility = "hide";}
	if (ns6) {document.getElementById([lay]).style.display = "none";}
}

function showlayer(lay) {
	hideall();
	//alert(ie4 + ':' + ns4 + ':' + ns6);
	if (ie4) {document.all[lay].style.visibility = "visible";}
	if (ns4) {document.layers[lay].visibility = "show";}
	if (ns6) {document.getElementById([lay]).style.display = "block";document.getElementById([lay]).style.visibility = "visible";}
}
function hideall() {
	hidelayer('subnav1');
	hidelayer('subnav2');
	hidelayer('subnav3');
	hidelayer('subnav4');
	hidelayer('subnav5');
}