Errors that force exchanges are mainly failures that affect the catalog functionality and that have not been registered in former operating tests.

The variety of hardware/software combinations that are in use on the customer side holds a permanent element of uncertainty that might result in such errors.

Furthermore, different levels of knowledge by the users might result in the fact that the programs are not always operated as intended by the programmer.

A simple and clear user interface helps to keep this source of error as little as possible.