<!--
if (document.images) {
  homeOn = new Image();
  homeOn.src = "home_on.gif";
  homeOff = new Image();
  homeOff.src = "home_off.gif";

  introOn = new Image();
  introOn.src = "button_ic_on.gif";
  introOff = new Image();
  introOff.src = "button_ic_off.gif";

  knotsOn = new Image();
  knotsOn.src = "button_class_adv_on.gif";
  knotsOff = new Image();
  knotsOff.src = "button_class_adv_off.gif";

  cirOn = new Image();
  cirOn.src = "button_img_cir_on.gif";
  cirOff = new Image();
  cirOff.src = "button_img_cir_off.gif";

  keyOn = new Image();
  keyOn.src = "button_img_key_on.gif";
  keyOff = new Image();
  keyOff.src = "button_img_key_off.gif";

  triOn = new Image();
  triOn.src = "button_img_tri_on.gif";
  triOff = new Image();
  triOff.src = "button_img_tri_off.gif";

  spiOn = new Image();
  spiOn.src = "button_img_spi_on.gif";
  spiOff = new Image();
  spiOff.src = "button_img_spi_off.gif";

  othOn = new Image();
  othOn.src = "button_img_oth_on.gif";
  othOff = new Image();
  othOff.src = "button_img_oth_off.gif";
}
function turnOn(imageName) {
  if (document.images) {
    document[imageName].src = eval(imageName + "On.src");
  }
}
function turnOff(imageName) {
  if (document.images) {
    document[imageName].src = eval(imageName + "Off.src");
  }
}
// -->