isamap = new Object();
isamap[0] = "_df"
isamap[1] = "_ov"
isamap[2] = "_ot"
isamap[3] = "_dn"

function isimgact(id, act)
{
	if(document.images) 
	document.images[id].src = eval( "isimages." + id + isamap[act] + ".src");
}

if (document.images) 
{ // ensure browser can do JavaScript rollovers.
isimages = new Object();
isimages.zurueck_df = new Image();
isimages.zurueck_df.src = "zurueck_low.jpg";

isimages.zurueck_ov = new Image();
isimages.zurueck_ov.src = "zurueck.jpg";

}