eon = new Image();
eon.src = "img_specific/ep.gif";
don = new Image();
don.src = "img_specific/dp.gif";
fon = new Image();
fon.src = "img_specific/fp.gif";


eoff = new Image();
eoff.src = "img_specific/e.gif";
doff = new Image();
doff.src = "img_specific/d.gif";
foff = new Image();
foff.src = "img_specific/f.gif";


function an(imgName) {
            if (document.images)  {
              document[imgName].src = eval(imgName + "on.src");
            }
}

function aus(imgName) {
            if (document.images)  {
              document[imgName].src = eval(imgName + "off.src");
            }

}