function newImage(arg) {
        if (document.images) {
                rslt = new Image();
                rslt.src = arg;
                return rslt;
        }
}

function changeImages() {
        if (document.images && (preloadFlag == true)) {
                for (var i=0; i<changeImages.arguments.length; i+=2) {
                        document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
                }
        }
}
var preloadFlag = false;
if (document.images) {
  graph01 = newImage("http://www.r4.com/GraphicsR4/0001.mar?ID=graf_ibex35_ind");
  graph02 = newImage("http://www.r4.com/GraphicsR4/0001.mar?ID=graf_euros50");
  graph03 = newImage("http://www.r4.com/GraphicsR4/0001.mar?ID=graf_nas100");
  preloadFlag = true;
}

function change(id, newClass) {
        identity=document.getElementById(id);
        identity.className=newClass;
}