if (document.images) {
            img1on = new Image();
            img1on.src = "images/1a.gif";
            img2on = new Image();
            img2on.src = "images/2a.gif";
            img3on = new Image();
            img3on.src = "images/3a.gif";
            img4on = new Image();
            img4on.src = "images/4a.gif";

            img1off = new Image();
            img1off.src = "images/1.gif";
            img2off = new Image();
            img2off.src = "images/2.gif";
            img3off = new Image();
            img3off.src = "images/3.gif";
            img4off = new Image();
            img4off.src = "images/4.gif";
        }

function imgOn(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "on.src");
        }
}


function imgOff(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "off.src");
        }
}


function MM_preloadImages() { //v3.0
  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
    var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}