title: Invalid role attribute value for section element?
body: <p>In a website I'm working on right now, I have a section element which type is set to "<code>main</code>". According to <a href="http://www.w3.org/html/wg/drafts/html/master/dom.html#wai-aria" rel="noreferrer">WAI-ARIA</a>, the <code>section</code> element can use <code>main</code> as <code>role</code> attribute (<code>role="main"</code>).</p>
  
  <p>However, when I run  my site through the W3C validator, I get a "Bad value main for attribute role on element section." error. I used the <code>main</code> value in another website previously, and it did pass the validation, but now it's no longer valid, reporting the same error.</p>
  
  <p>Has the HTML5 specification changed recently and took out the <code>main</code> value? Should I believe the WAI-ARIA or the W3C validator? Is the WAI-ARIA page out of date? Should I just keep the <code>section</code> element without any role attribute (which will revert to the "region" default value)?</p>
  
  <p>Any thoughts and tips on this would be appreciated :)</p>