var img = new Array();

function sOn(nam) {
  if (document.images) {
    var old = document.images[nam].src;
    var off = old.lastIndexOf(".gif");
    document.images[nam].src = old.substring(0,off) + "_LT.gif";
  }
}

function sOff(nam) {
  if (document.images) {
    var old = document.images[nam].src;
    var off = old.lastIndexOf("_LT.gif");
    document.images[nam].src = old.substring(0,off) + ".gif";
  }
}

function ImgPreFetch() {
  var j = 0;
//  alert(document.images.length);
  for (i=0;i<document.images.length;i++) {
    if (document.images[i].name != '') {
      img[j] = new Image();
      img[j++].src = document.images[i].src.slice(0,-4) + '_LT.gif';
      }
    }
}