function imgOver(imgDir, imgName, imgExt) {

    var cDir = (imgDir == null) ? "images/" : imgDir;
    var cExt = (imgExt == null) ? "_o.gif" : imgExt;

    if (document.images) {
      currentImage = document.images[imgName];
      currentImage.src = cDir + imgName + cExt;
    }
  }



  function imgOut(imgDir, imgName, imgExt) {

    var cDir = (imgDir == null) ? "images/" : imgDir;
    var cExt = (imgExt == null) ? ".gif" : imgExt;

    if (document.images) {
      currentImage = document.images[imgName];
      currentImage.src = cDir + imgName + cExt;
    }
  }