title: HTML ARIA validation issues (HTML5)
body: <p>I pretty much make sure my website(s) always validates.</p>
  
  <p>So today, after changing a certain item on my website, I ran the W3C validator once again.</p>
  
  <p>And suddenly got about 20 errors - which weren't there on thursday (2 days ago).</p>
  
  <p>(For my validation I chose HTML5 / UTF8 - just like last time)</p>
  
  <p>For some reason I now get a:</p>
  
  <blockquote>
    <p>Element <code>li</code> is missing one or more of the following attributes: aria-checked, aria-expanded, aria-valuemax, aria-valuemin, aria-valuenow, aria-valuetext, role."-error for every list item I use.</p>
  </blockquote>
  
  <p>Is ARIA mandatory, and if so why do I suddenly get these errors - when I did not two days ago?</p>
  
  <p>It could be that I'm overlooking something. My website can be found here: <a href="http://www.project-voorbeeld3.be/" rel="nofollow">http://www.project-voorbeeld3.be/</a></p>
  
  <p>I have to admit, ARIA is new to me at this point - but I've looked through quite a lot of articles about it, and I just can't seem to figure out what is wrong.</p>
  
  <p>Any clues would be welcome!</p>