The automotive industry as a key user group for CAD systems, recognising product data representation and exchange as a matter of high strategic importance for the future, has made tremendous e orts to create an international standard for automotive design data, the STEP AP214. This project was originally initiated by the German VDA, but experts from the US, Japan, France, Sweden, and other European countries have long since involved themselves actively in these discussions.

The STEP standard has been under development since 1983, and many CAD system vendors have been working on prototype implementations of STEP for years.

Today, a CAD user can buy a variety of STEP AP214 processors (or he gets them with his CAD system updates). Consequently, the users organised in the ProSTEP association have high information requirements on the capabilities of these processors.

1996, the ProSTEP association established a regular activity, the benchmark, to address the question of what quality the available STEP translators are o ering to the end user.

Now, for the fourth time, we take a look at the current situation. The vendors have released new and improved versions of their translators. Assemblies and presentation, newly introduced to the third benchmark's scope, meanwhile have been implemented broadly. For these reasons, the results of the former benchmarks are no more reecting the state of STEP implementation that is currently available.

The fourth benchmark was conducted in order to provide an update to the members of the ProSTEP association: it was performed using the STEP translators that were available at the beginning of September 1998.

This benchmark documents the capabilities in exchange of solid, surface, assembly and presentation data.

At this point we would like to thank all the participating system vendors whose kind donations of hardware and software made the Benchmark possible. All the same we appreciate the e ort of users providing the appropriate test cases.