var delay = 5;
ie4 = ((navigator.appName == "Microsoft Internet Explorer") && (parseInt(navigator.appVersion) >= 4 ))
ns4 = ((navigator.appName == "Netscape") && (parseInt(navigator.appVersion) >= 4 ))

if (ns4) {
    layerRef="document.layers";
    styleRef="";
} else {
    layerRef="document.all";
    styleRef=".style";
}       

function afficheCalque(calque)
{
eval(layerRef + '["' + calque +'"]' + styleRef + '.visibility = "visible"');
}

function cacheCalque(calque)
{
  eval(layerRef + '["' + calque +'"]' + styleRef + '.visibility = "hidden"');
}