var out=""; 
var limg=""; 

function off() {
if (out=="") { return; } 
if (document.images) {
document.images[limg].src=out;
out="";
}
} 

function on(img,o1,o2) {
if (document.images) { 
if (out != "") { off(); } document.images[img].src=o1;
out=o2;
limg=img;
}
}