bdi elementdir global attribute has special semantics on this element.HTMLElement.The bdi element represents a span of
  text that is to be isolated from its surroundings for the purposes
  of bidirectional text formatting. [BIDI]
The dir global
  attribute defaults to auto on
  this element (it never inherits from the parent element like with
  other elements).
This element is especially useful when embedding user-generated content with an unknown directionality.
In this example, usernames are shown along with the number of
   posts that the user has submitted. If the bdi element
   were not used, the username of the Arabic user would end up
   confusing the text (the bidirectional algorithm would put the colon
   and the number "3" next to the word "User" rather than next to the
   word "posts").
<ul> <li>User <bdi>jcranmer</bdi>: 12 posts. <li>User <bdi>hober</bdi>: 5 posts. <li>User <bdi>إيان</bdi>: 3 posts. </ul>