window.onload=assignments;

function assignments() {
	var nav = document.getElementById('nav');
	var lists = nav.getElementsByTagName('ul');
	var items = lists[0].getElementsByTagName('li');
	var num = items.length;
	addEvent(items[9],'mouseover',show_sub);
	addEvent(items[9],'mouseout',hide_sub);
}

function show_sub() {
	var sub_menu = this.getElementsByTagName('ul');
	sub_menu[0].style.display = 'block';
}
function hide_sub() {
	var sub = this.getElementsByTagName('ul');
	sub[0].style.display = 'none';
}



/*http://onlinetools.org/articles/unobtrusivejavascript/chapter4.html*/
function addEvent(obj, evType, fn, useCapture){
  if (obj.addEventListener){
    obj.addEventListener(evType, fn, useCapture);
    return true;
  } else if (obj.attachEvent){
    var r = obj.attachEvent("on"+evType, fn);
    return r;
  } else {
    alert("Handler could not be attached");
  }
}