Why is Application Inheritance Important?

VTS has been structured so that one application can inherit and then expand upon the features of another application. You can think of each application as a building block, with the top-most blocks inheriting the features of the blocks upon which they are based. Thus, a custom tag type or set of graphics added to a lower application are instantly available to the upper layers.

Reusability: Inheritance from lower application layers to upper application layers ensures reusability of the features and functionality of the lower layers. For example, if you have a custom layer that contains a set of custom tag types, you can use that custom layer as the basis for multiple application layers, all of which will have access to your custom objects.

Extensibility: New functionality can easily be "plugged in" to a lower layer without changing the structure of all upper layers that are based upon it.  For example, the custom tag added to a lower level can be extended with new features. As long as the older features are not changed, applications built upon this layer will continue to work without interruption.