German public libraries use these records and a children's OPAC fed with other than these data did not seem acceptable for economic reasons. Future users of the system participate in the process of software development completely and as early as possible. Evolutionary system development implies that the development is cyclical and software versions are based on each other. Software engineering is not a linear process which translates users' requests into a program like an engineering process. Thus, for example, in the beginning of our project it was not possible to even name all requirements.
Requirements emerge, grow and change during the project and by using the software.
Users Software users as a rule are experts in the area of application. This is not the case for our target group as children are no library experts. However, they are experts as far as their reading behaviour, their personal classification of books and their judgement on books are concerned. These were 3rd grade school children aged between 8 and 9 years. Findings from this evaluation have left their marks upon our present prototype.