RadDropDownTree supports binding to various types of data sources, including declarative
    datasources.
    
        Some of the declarative data sources like the XmlDataSource and the SiteMapDataSourceare inherently hierarchical. 
        Therefore when data-bound to these types of data sources, RadDropDownTree automatically creates the node hierarchy.
        There is no need to use the DataFieldID and DataFieldParentID
        properties.
    
      
        RadDropDownTree supports binding to an ObjectDataSource as well. In
        addition to the standard Entry properties (Text, Value, etc.) that
        can be bound to the underlying business objects, the DataFieldID
        and DataFieldParentID properties can be specified, too. In this
        way, RadDropDownTree can create a hierarchy of Entries.
    
    
        Still, the business objects should provide the data needed for the RadDropDownTree to
        build the hierarchy. If the ParentID property of the business objects are of nullable
        or reference type, then null values denote root Entry. In case, the ParentID property
        is of value type (Integer, Guid, etc.), '0'/'Guid.Empty' values denote the root
        Entry.