The error messages are not always easy to understand. Messages about processes are usually not available. It is not always clear to the user how to recover from an error. The user interface usually consists of questions to be answered by the user or a list of options. Undo facilities are usually not available.
Little information is displayed on the current program module.
The input format is not always checked on correctness. B. file input The program can read data files with a specific format, described in appendix tables of the user manual. The user can choose between statistics that cannot be modified. All these statistics can be displayed on the screen. The statistics that can be displayed can be written to an ascii file.