if (document.images) {
img1 = new Image();
img1.src = "images/frontlink1a.jpg";
img2 = new Image();
img2.src = "images/frontlink2a.jpg";
img3 = new Image();
img3.src = "images/frontlink3a.jpg";
}

function frontlinkOn(num)
{
document.images['frontlink' + (num)].src = "images/frontlink"+(num)+"a.jpg"
}

function frontlinkOff(num)
{
document.images['frontlink' + (num)].src = "images/frontlink"+(num)+".jpg"
}