VSO is a Personal Computer application that executes from the Windows operating system. As such, it has a familiar user interface similar to MS Word and PowerPoint. At one level it is simply a drawing tool that can be used to describe operations and systems. The user selects objects (aircraft, computer, business activity, etc.) from a tool bar and drags and drops them in a design area.

The objects can be connected together to show information and data flow appropriate for a proposed architecture. However, a number of important functions are being performed beneath the surface that verify and validate the architecture. Although the user is not explicitly aware of it, he is actually describing the architecture as a Colored Petri Net (CPN).

The objects (library objects are available or the user can build custom objects and store them for re-use) have embedded within themselves a complete mathematical description of their static and dynamic properties.

This means that the architectures developed in VSO can be made to evolve over time by simply clicking a Start button. Evolution over time occurs because VSO objects contain the business rules that dictate their behavior ? that is, the changes in the values of the architecture?s attributes that occur as explicit functions of time or upon the occurrence of an event.