aus = new Image();
 ein = new Image();
 aus.src   = "./img/aus.gif";
 ein.src   = "./img/ein.gif";
clicked="";

function hiLite (imgDocID,imgObjName) {
if(imgDocID != clicked){
 document.images[imgDocID].src=eval(imgObjName + ".src");
}
}

function doIT(){
document.images[clicked].src=eval("ein" + ".src");
}