ns4 = (document.layers)? true:false
ie4 = (document.all)? true:false
v6 = (document.getElementById)? true:false

//Layer anzeigen
function showlayer(layerid)
{
 if (ns4) document.layers[layerid].visibility = "show"
 else if (v6) document.getElementById(layerid).style.visibility = "visible";
 else if (ie4) document.all[layerid].style.visibility = "visible"
}

//Layer verstecken
function hidelayer(layerid)
{
 if (ns4) document.layers[layerid].visibility = "hide"
 else if (v6) document.getElementById(layerid).style.visibility = "hidden";
 else if (ie4) document.all[layerid].style.visibility = "hidden"
}