ns4 = (document.layers) ? true:false //required for Functions to work
ie4 = (document.all) ? true:false //required for Functions to work
ng5 = (document.getElementById) ? true:false //required for Functions to work

function hideSec() {
if (ng5) document.getElementById('sec1').style.visibility = "hidden"
else if (ns4) document.sec5.visibility = "hide"
else if (ie4) sec5.style.visibility ="hidden"
}

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