title: What HTML elements are not tabbable even with tabindex?
body: <p>Does anyone have a list of the HTML (HTML5) elements that are <strong>not</strong> tabbable, even if a tabindex is specified? (By tabbable, I mean that they can receive the focus through repeatedly pressing the "tab" key.)</p>
  
  <p>We know that there are those elements which are tabbable by default, such as <code>input</code> or <code>textarea</code>. We also know that there are some elements which are only tabbable if a tabindex is explicitly specified, such as <code>div</code> and <code>span</code> elements.</p>
  
  <p>According to W3Schools, "In HTML5, the tabindex attribute can be used on any HTML element". However, there are surely some elements which are not tabbable even if they have a tabindex. For example, it makes no sense for the <code>param</code> element to be tabbable, or the <code>head</code> element. I also don't really think it's possible for the <code>option</code> element to be tabbable, but I'm not sure about that. And I'm even less sure about things like <code>map</code> which can contain tabbable elements but are not usually tabbable themselves.</p>
  
  <p>Can someone give me a list of all the elements that can never receive focus even if they have a tabindex?</p>