The reduction of the effort required for integration of a module into a production plant is the fundamental aim of modular plant architectures. Effective module integration can be achieved, for instance, by shifting engineering efforts from the classical site-engineering to the engineering of plant modules. The basis of this approach is the formal description of various aspects of a module in a module type package (MTP). The core elements of this MTP are presented in this paper and discussed in terms of use in a standard module description. In addition, this paper presents a transformation of this concept to the standardized format AutomationML.