if (document.images) {

	// nav over images
    img1on = new Image();
    img1on.src = "images/elements/nav/national_on.gif";
    img2on = new Image();
    img2on.src = "images/elements/nav/north_on.gif";
    img3on = new Image();
    img3on.src = "images/elements/nav/west_on.gif";
    img4on = new Image();
    img4on.src = "images/elements/nav/east_on.gif";
    img5on = new Image();
    img5on.src = "images/elements/nav/agri_affairs_on.gif";
    img6on = new Image();
    img6on.src = "images/elements/nav/international_on.gif";
    img7on = new Image();
    img7on.src = "images/elements/nav/ssts_on.gif";

	// nav off images
    img1off = new Image();
    img1off.src = "images/elements/nav/national_off.gif";
    img2off = new Image();
    img2off.src = "images/elements/nav/north_off.gif";
    img3off = new Image();
    img3off.src = "images/elements/nav/west_off.gif";
    img4off = new Image();
    img4off.src = "images/elements/nav/east_off.gif";
    img5off = new Image();
    img5off.src = "images/elements/nav/agri_affairs_off.gif";
    img6off = new Image();
    img6off.src = "images/elements/nav/international_off.gif";
    img7off = new Image();
    img7off.src = "images/elements/nav/ssts_off.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");
        }
}