A provider can display if any base table is allowed in the Designer or if the hierarchy of data sources has to be maintained.

A typical example would be customers/orders in a XML file. If inserting "orders" would be allowed on the root level, randomly only the orders of the first customer would be displayed. The below example shows how to avoid that for the XmlDataProvider Class. By that it is only possible to directly insert the customer and to insert the orders one level deeper.