if (document.images)  {
img1on = new Image();
img1on.src = "images/exp_btn_search_on.gif";
img1off = new Image();
img1off.src = "images/exp_btn_search.gif";

img2on = new Image();
img2on.src = "images/exp_btn_about_on.gif";
img2off = new Image();
img2off.src = "images/exp_btn_about.gif";

img3on = new Image();
img3on.src = "images/exp_btn_about_data_on.gif";
img3off = new Image();
img3off.src = "images/exp_btn_about_data.gif";

img4on = new Image();
img4on.src = "images/exp_btn_local_on.gif";
img4off = new Image();
img4off.src = "images/exp_btn_local.gif";

img5on = new Image();
img5on.src = "images/exp_btn_help_on.gif";
img5off = new Image();
img5off.src = "images/exp_btn_help.gif";
}


function imgSwap (imgName,imgFile)  {
        if (document.images)  {
                document.images[imgName].src = eval (imgFile + ".src");
        }
}