W3C Validation for Drupal 7 HTML5 + RDFa June 20, 2012 in Development, Drupal 2 Comments on this post. Maher B Thank you for this great article. I managed to do like it is mentionned above and It works fine. However, When cheking, with validator.w3.org/nu, I got one error for the attribute xml:lang which is empty in drupal 7. ‘ class=”username” xml:lang=”" about=”/users/admin” typeof=”sioc:UserAccount” property=”foaf:name”. I hope, you have an Idea about it. http://twitter.com/Tekl Tekl Hi, thanks for the article. It seems that there are some slashes missing. I hope you can correct that.