function showhide(zichtbaar,nietzichtbaar) {

if (document.all) { //IS IE 4 or 5 (or 6 beta)
    eval( "document.all." + zichtbaar + ".style.visibility = 'visible'");
    eval( "document.all." + nietzichtbaar + ".style.visibility = 'hidden'");    
}
if (document.layers) { //IS NETSCAPE 4 or below
    document.layers[zichtbaar].visibility = "'visible'";
    document.layers[nietzichtbaar].visibility = "'hidden'";
}
if (document.getElementById && !document.all) {
    maxwell_smart = document.getElementById(zichtbaar);
    maxwell_smart.style.visibility = "'visible'";
    maxwell_smart1 = document.getElementById(nietzichtbaar);
    maxwell_smart1.style.visibility = "'hidden'";
}
}