var n3 = false;
image1       = new Image();
image1.src   = "art2off.gif";
image1on     = new Image();
image1on.src = "art2on.gif"

image2       = new Image();
image2.src   = "artoff.gif";
image2on     = new Image();
image2on.src = "arton.gif"

function on3(name)
{
    document[name].src = eval(name + "on.src");
}

function off3(name)
{
    document[name].src = eval(name + ".src");
}

n3 = true;
function on(name)
{
   if (n3)
      on3(name);
}

function off(name)
{
   if (n3)
      off3(name);
}