ns4 = (document.layers) ? true:false
ie4 = (document.all) ? true:false 
ng5 = (document.getElementById) ? true:false 

function hideLayer(n) {
if (ng5) document.getElementById(n).style.visibility = "hidden";
else if (ns4) document.layers[n].visibility = "hide";
else if (ie4) document.all[n].style.visibility ="hidden";
}

function showLayer(n) {
if (ng5) document.getElementById(n).style.visibility = "visible";
else if (ns4) document.layers[n].visibility = "show";
else if (ie4) document.all[n].style.visibility = "visible";
}