The discussion of Systems versus Toolkits was interesting. Visualization systems include tools such as LYMB, Iris Explorer, Data Explorer and AVS. Toolkits include packages such as Iris Inventor, ISG’s IAP, and the Visualization Toolkit (vtk). Systems are self-contained, often turn-key, offer great reuse, have an integrated UI, but they are an all-or-nothing approach. They do not readily embed within another application framework. Toolkits are more adaptable, allowing you to use only what you need and are generally independent of the UI. Bill described the evolution of visualization within GE CRD from the LYMB system approach to into the VTK. While LYMB had a lot of good things, it was a very proprietary system. VTK, on the other hand, is an open source toolkit. It started as an example implementation for a textbook and became successful in its own right. It is available on the web at http://www.kitware.com/vtk.html It embodies several lessons learned from the earlier implementation. In particular vtk does not include an interpreter as LYMB did. Instead, while it is implemented in C++, vtk relies on tcl, java or python for scripting.