A network of processing devices is arranged to communicate by packets having an addressing header and a data portion. The focusing control apparatus of the invention includes an evaluating unit and a control module. Then, the first area is considered as a defective area, and the new data is recorded in a second area. Furthermore, there is disclosed a method for printing a three-dimensional object using various suitable materials. A virtually real-time inspection or a comparison can be made with previously taken underbody images of the same moving vehicle or with vehicle manufacturers’ data for the same vehicular models. The invention furthermore relates to a process for testing a memory and to a memory module.