var DOM=new Object();
DOM.getElementById=function(id) {
	if(document.getElementById) { return document.getElementById(id); }
	if(document.layers) { return document.layers[id]; }
	if(document.all) { return document.all[id]; }
	return null;
}
function swap(img,on) {
	image=DOM.getElementById(img);
	if(image!=null) {
		state=(on)?'on':'off';
		image.setAttribute('src', 'images/'+img+state+'.gif');
	}
}
function swapMain(img) {
	main=DOM.getElementById('main-image');
	if(main!=null) {
		main.setAttribute('src', 'images/'+img+'.gif');
	}
}