Visual Querying and Exploration of Large Answers in XML Databases with X²

  This paper describes X² (eXploring XML data), a system for
  efficiently querying XML data and visually exploring answer sets,
  with a special focus on the novel user interface for interaction
  with the query result. The process of querying XML documents is
  performed interactively and in a completely graphical manner.
  Special attention was paid to simplicity of the user interface: In a
  first step the user submits a query to the system and gets the
  result presented in the form of a Complete Answer Aggregate (CAA).
  CAAs visually (re)present the answer space in a compact form and
  thus provide a good overview over the set of all answers. They offer
  a rich variety of presentation modes and exploration techniques
  which are used in the second step to interactively explore the
  answer space.