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"');}