The Tree UI element displays hierarchical structures. Each Tree UI element contains a number of tree nodes either of the type TreeNodeType or TreeltemTyp. They describe which data is displayed below the top-level context node. The context node is bound by the Tree property dataSource. The only difference between the TreeNodeType element and the TreeltemType element is that the tree node type TreeNodeType can have children, whereas the type TreeltemType can display the leaves of a tree, but cannot have children.
The hierarchical structure of the tree UI element must be represented in the context. This is possible by specifying a certain number of levels in the context at design time. For example: Customer à Order à OrderItems..
Or you can create a recursive node in the context. In this case, a virtual node points to a parent node at design time. At runtime, a specific property of the context node allows to add non-singleton child nodes that need to be of the same type as the ones they are pointing to. In so doing, you specify – at design time - a context structure with recursive nodes that can have any number of levels at runtime.