var nn4 = (navigator.appName.indexOf("Netscape") > -1 && navigator.appVersion.indexOf("4") > -1) ? true:false                 
var ie = (document.all) ? true:false
var nn6 = (document.getElementById && !document.all) ? true:false

function browser(id){
var layer = (nn4) ? document.layers[id] : (ie) ? document.all[id] : document.getElementById(id)
return layer
}

function showLayer(id) {
layer = browser(id)
   if(nn4){
   layer.visibility = "visible"
   }
   else{
   layer.style.visibility = "visible"
   }
}

function hideLayer(id) {
layer = browser(id)
   if(nn4){
   layer.visibility = "hidden"
   }
   else{
   layer.style.visibility = "hidden"
   }
}