The RadChart control displays drill down data in a hierarchical manner. In order to define the different level of the drill down hierarchy you have to use the HierachicalViewDescriptors property of the RadChart control. It is a collection which contains ChartHierarchicalViewDescriptor objects. The ChartHierarchicalViewDescriptor object is used to define a hierarchy level. The level of the descriptor in the hierarchy depends on the position it has in the collection.