As mentioned in the overview, an assembly forms on of the important aspects of a system. A system consists of an assembly and an allocation as described in section . The first specifies how the components are connected with other components, the latter specifies how the components and connectors are mapped to hardware and middleware environments. Systems can be seen as special kind of composite components - with the visibility differences mentioned above and the fact that an allocation is also provided. Systems are not supposed to be reused as components are. The are assumed to be coupled by using special techniques for system integration.