Should we put <ul> tag inside <nav> tag?
===

I wonder many websites put <ul> tag inside <nav> tag, from the specification the nav tag has anchors tags, and here the example in [w3schools][1], why many sites make like this:

     <nav>
            <ul>
                <li><a href="#">Home</a></li>
                <li><a href="#">About</a></li>
            </ul>
        </nav>
Is that correct or we should only make like this

     <nav>
           <a href="#">Home</a>
           <a href="#">About</a>
      </nav>

  [1]: http://www.w3schools.com/html5/tag_nav.asp