In this model, attribute values for the derived object can override attribute values for the base object. Put another way, when values aren’t provided for the derived object, the base values will “bubble up.”
Imagine a base content object with its attribute labels and values printed on a piece of paper. Lay that piece of paper on a flat surface, then print another content object out in the same format. For values you want to inherit from the base object, simply cut them out of the second paper, leaving holes where they were. Lay the second object on top of the first, and some values from the base object will show through the holes, while others will be covered up.
Effectively, the base object provides default attribute values which can change in real-time. The derived object – which is sometimes called a variation – overrides those values when desired.