function auf(menu) {
// DOM ALLE NEUEN BROWSER
if (document.getElementById) {
document.getElementById(menu).style.visibility="visible";}
// IE 5
if (document.all) {
document.all[menu].style.visibility="visible";}
// NN 4
if (document.layers) {
document.layers[menu].visibility="visible";}}
function zu(menu) {
if (document.getElementById) {
document.getElementById(menu).style.visibility="hidden";}
if (document.all) {
document.all[menu].style.visibility="hidden";}
if (document.layers) {
document.layers[menu].visibility="hidden";}}