if (document.images) {

mton = new Image();
mton.src = "buttons/mt2.gif";
mtoff = new Image();
mtoff.src = "buttons/mt1.gif";

mt_tyaon = new Image();
mt_tyaon.src = "buttons/mt_tya2.gif";
mt_tyaoff = new Image();
mt_tyaoff.src = "buttons/mt_tya1.gif";

hison = new Image();
hison.src = "buttons/h2.gif";
hisoff = new Image();
hisoff.src = "buttons/h1.gif";

onson = new Image();
onson.src = "buttons/on2.gif";
onsoff = new Image();
onsoff.src = "buttons/on1.gif";

tson = new Image();
tson.src = "buttons/ts2.gif";
tsoff = new Image();
tsoff.src = "buttons/ts1.gif";

newson = new Image();
newson.src = "buttons/sn2.gif";
newsoff = new Image();
newsoff.src = "buttons/sn1.gif";

cdon = new Image();
cdon.src = "buttons/cd2.gif";
cdoff = new Image();
cdoff.src = "buttons/cd1.gif";

gon = new Image();
gon.src = "buttons/g2.gif";
goff = new Image();
goff.src = "buttons/g1.gif";

sson = new Image();
sson.src = "buttons/ss2.gif";
ssoff = new Image();
ssoff.src = "buttons/ss1.gif";

son = new Image();
son.src = "buttons/s2.gif";
soff = new Image();
soff.src = "buttons/s1.gif";

bkon = new Image();
bkon.src = "buttons/nav_back.gif";
bkoff = new Image();
bkoff.src = "buttons/nav_back_off.gif";

topon = new Image();
topon.src = "buttons/nav_top.gif";
topoff = new Image();
topoff.src = "buttons/nav_top_off.gif";

smon = new Image();
smon.src = "buttons/nav_site-map.gif";
smoff = new Image();
smoff.src = "buttons/nav_site-map_off.gif";

emon = new Image();
emon.src = "buttons/nav_e-mail.gif";
emoff = new Image();
emoff.src = "buttons/nav_e-mail_off.gif";
}
function roll(imgName, imgSrc)
{
if (document.images)
{
document[imgName].src=eval(imgSrc + ".src");
}
}