function on(nameImage) {
document [nameImage].src = eval(nameImage+"_on.src");
}
function off(nameImage){
document [nameImage].src = eval(nameImage+"_off.src"); 
}
/*
misschien later nog nodig...!?

function off_direct(nameImage, status){
if (status == "off")
document [nameImage].src = eval(nameImage+"_off.src");
} 

function sub_on(nameImage, image) {
document [nameImage].src = eval(image+".src"); 
}
function sub_off(nameImage, image) {
document [nameImage].src = eval(image+".src");
}*/