if ((navigator.appName == "Netscape" && parseInt(navigator.appVersion) >= 3)
|| (parseInt(navigator.appVersion) >= 4))
        version = "ok";
        else version = "?";

if (version == "ok")
{
        var imgDir = "img/";

n0on = new Image();
n0on.src = imgDir + "btnAeroporto_on.jpg";
n0off = new Image();
n0off.src = imgDir + "btnAeroporto.jpg"; 

n1on = new Image();
n1on.src = imgDir + "btnParcheggi_on.jpg";
n1off = new Image();
n1off.src = imgDir + "btnParcheggi.jpg"; 

n2on = new Image();
n2on.src = imgDir + "btnTreno_on.jpg";
n2off = new Image();
n2off.src = imgDir + "btnTreno.jpg"; 

n3on = new Image();
n3on.src = imgDir + "btnBus_on.jpg";
n3off = new Image();
n3off.src = imgDir + "btnBus.jpg"; 

n4on = new Image();
n4on.src = imgDir + "btnMacchina_on.jpg";
n4off = new Image();
n4off.src = imgDir + "btnMacchina.jpg"; 	



}

 function turnOn(img) {
   if (version == "ok")
	{
  	eval("document."+img).src = eval(img+"on").src;
	}
}

 function turnOff(img) {
   if (version == "ok")
	{
   	eval("document."+img).src = eval(img+"off").src;
	}
}