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

function hideNoc() { 

if (ng5) document.getElementById('noc1').style.visibility = "hidden"; 
else if (ns4) document.noc1.visibility = "hide"; 
else if (ie4) noc1.style.visibility ="hidden"; 

if (ng5) document.getElementById('noc2').style.visibility = "hidden"; 
else if (ns4) document.noc2.visibility = "hide"; 
else if (ie4) noc2.style.visibility ="hidden"; 

if (ng5) document.getElementById('noc3').style.visibility = "hidden"; 
else if (ns4) document.noc3.visibility = "hide"; 
else if (ie4) noc3.style.visibility ="hidden"; 

if (ng5) document.getElementById('noc4').style.visibility = "hidden"; 
else if (ns4) document.noc4.visibility = "hide"; 
else if (ie4) noc4.style.visibility ="hidden"; 

if (ng5) document.getElementById('noc5').style.visibility = "hidden"; 
else if (ns4) document.noc5.visibility = "hide"; 
else if (ie4) noc5.style.visibility ="hidden"; 
}

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

function hideIce() {
if (ng5) document.getElementById('ice').style.visibility = "hidden"; 
else if (ns4) document.noc1.visibility = "hide"; 
else if (ie4) noc1.style.visibility ="hidden"; 
}

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