<https://chieftalk.chiefarchitect.com/topic/35602-how-to-clip-display-reference/#comment-274506>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://chieftalk.chiefarchitect.com/topic/35602-how-to-clip-display-reference/?tab=comments#comment-274491>