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;
function preloadImages() {
  if (document.images) {
    trnav_02_over = newImage("/images/trnav_02-over.gif");
    trnav_03_over = newImage("/images/trnav_03-over.gif");
    trnav_04_over = newImage("/images/trnav_04-over.gif");
    trnav_05_over = newImage("/images/trnav_05-over.gif");
    trnav_06_over = newImage("/images/trnav_06-over.gif");
    trnav_07_over = newImage("/images/trnav_07-over.gif");
    trnav_08_over = newImage("/images/trnav_08-over.gif");
    preloadFlag = true;
  }
}