//swaps rollover images
//original image file name must contain '0' before the extension
//rollover image file name must contain '1' before the extension
//the <a> tag must have onMouseOver="swap('id') onMouseOut="swap('id')
function swap(id) {
	var source = document.getElementById(id).src;
	var root = source.substring(0, source.lastIndexOf('.') - 1);
	var state = source.substring(source.lastIndexOf('.') - 1, source.lastIndexOf('.'));
	var extension = source.substring(source.lastIndexOf('.'));
	
	if(state == "0")
		document.getElementById(id).src = root + "1" + extension;
	else if(state == "1")
		document.getElementById(id).src = root + "0" + extension;
}