The Bremen Institute of Industrial Technology and Applied Work Science at the University of Bremen (BIBA) has developed a system for proctuction-coordination in the shipbuilding industry to support the decentralization of production planning. The system development was topic of the ESPRIT MUSYK project sponsored by the European Commission and of the ITiS-E project, sponsored by the former BMFT (German Ministry for Research and Technology). This application, so called GIGROS, supports long- and middle-term production-planning of complex one-of-a-kind products. Considering the involved software-systems concurrent manufacturing demands a transition from centralized towards increasingly decentralized models of control and action. Our goal has to be to support decentralized planning entities, each of them being equipped with a GIGROS-system. A main challenge is the co ordination and synchronization of activities within those complex systems.