The Tree View feature is being developed to enable users to explore the actual structure of an XML file in alignment with an associated XML Schema Definition (XSD) or Document Type Definition (DTD). This feature provides a visual representation of the hierarchical structure of the XML format, showcasing the relationships between elements, attributes, and their respective values. By visualizing the possible structure of the XML file alongside the XML file, users can easily identify any discrepancies or inconsistencies between the file and its associated schema, ensuring adherence to the defined structure.

This is a screenshot of the DocBook structure. It is easy to see which elements are optional "0..1" and which are choices "C". The "S" means sequence, so in this case "title", "subtitle" and "titleabbrev" have to be at the top of the "book" element and in this order. The half filled boxes mean that these elements allow text directly in them.

A click on the plus sign reveals what child elements can appear inside this element.