Abstract: The invention concerns a method, device and computer program medium for setting up a part of a computer system as well as such a computer system including a number of modules of different types using data in a number of data fields provided in a system data set. The computer program medium comprises computer program code providing data field definitions for the data fields of the system data set, said data field definitions being provided in a system data definition structure, where the system data definition structure groups the various data field definitions for the data fields of the system data set into data packages according to which modules are to use them, and the data field definitions include data enabling the generating of data handling units for handling data in the data fields of said system data set.