function toggle(id,ref) {
	var currentState = null;
	var id = document.getElementById(id);
	currentState = id.style.display;
	if(currentState == null || currentState == "none") {
		id.style.display = 'block';
		ref.src = './images/page/minus.gif';
	} else {
		id.style.display = 'none';
		ref.src = './images/page/plus.gif';
	}
}