This illustration shows the hierarchy of a sample application for a courier company. The top level table contains a table for vehicles with rows for the VID (vehicle ID), LastMaint (last maintenance) and LoadCap (load capacity). Below are three other tables for TRUCK, CAR and BICYCLE. In addition to a row that is specific to each, they all inherit the three rows that appear in the VEHICLE table, that is VID, LastMaint and LoadCap.