var NS4 = (document.layers) ? 1 : 0;
var IE4 = (document.all) ? 1 : 0;
var DOM = (document.getElementById) ? 1 : 0;
var ver4 = (NS4 || IE4) ? 1 : 0;

function SetImage(image_doc, image_mem) {
  if (!(document.images)) return;

  if (document[image_doc]) {
    document[image_doc].src = eval(image_mem + ".src");
  }

  if (NS4) {
    for (lname in document.layers) {
      l = document.layers[lname];
      if (l.document) {
        if (l.document[image_doc]) {
          l.document[image_doc].src = eval(image_mem + ".src");
      } }
    }
  }
}

img0 = new Image();
img0.src = "0.gif";
img1 = new Image();
img1.src = "1.gif";