if (document.images) {

//on
img1on = new Image();
img1on.src = "images/mainr_06.gif";

img2on = new Image();
img2on.src = "images/mainr_07.gif";

img3on = new Image();
img3on.src = "images/mainr_08.gif";

img4on = new Image();
img4on.src = "images/mainr_09.gif";

img5on = new Image();
img5on.src = "images/mainr_10.gif";

img6on = new Image();
img6on.src = "images/mainr_11.gif";

img6bon = new Image();
img6bon.src = "images/mainr_12.gif";

img7on = new Image();
img7on.src = "images/mainr_21.gif";

img8on = new Image();
img8on.src = "images/mainr_23.gif";

img9on = new Image();
img9on.src = "images/mainr_21.gif";

img10on = new Image();
img10on.src = "images/mainr_23.gif";

img11on = new Image();
img11on.src = "images/mainr_21.gif";

img12on = new Image();
img12on.src = "images/mainr_23.gif";

img13on = new Image();
img13on.src = "images/mainr_38.gif";

img14on = new Image();
img14on.src = "images/mainr_23.gif";

img15on = new Image();
img15on.src = "images/mainr_21.gif";

img16on = new Image();
img16on.src = "images/mainr_23.gif";

//off
img1off = new Image();
img1off.src = "images/main_06.gif";

img2off = new Image();
img2off.src = "images/main_07.gif";

img3off = new Image();
img3off.src = "images/main_08.gif";

img4off = new Image();
img4off.src = "images/main_09.gif";

img5off = new Image();
img5off.src = "images/main_10.gif";

img6off = new Image();
img6off.src = "images/main_11.gif";

img6boff = new Image();
img6boff.src = "images/main_12.gif";

img7off = new Image();
img7off.src = "images/main_21.gif";

img8off = new Image();
img8off.src = "images/main_23.gif";

img9off = new Image();
img9off.src = "images/main_21.gif";

img10off = new Image();
img10off.src = "images/main_23.gif";

img11off = new Image();
img11off.src = "images/main_21.gif";

img12off = new Image();
img12off.src = "images/main_23.gif";

img13off = new Image();
img13off.src = "images/main_38.gif";

img14off = new Image();
img14off.src = "images/main_23.gif";

img15off = new Image();
img15off.src = "images/main_21.gif";

img16off = new Image();
img16off.src = "images/main_23.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");
}
}