The first decision is to decide at what level types are needed. Typically, each Serverwill provide one Server Objectwith a well-known NodeId. The NodeIdsof the containing Nodesare also well-known because their symbolic name is specified in this standard and the NodeIdis based on the symbolic name in OPC 10000-6. Nevertheless, aggregating Serversmay want to expose the Server Objectsof the OPC UA Serversthey are aggregating in their AddressSpace. Therefore, it is very helpful to have a type definition for the Server Object. The Server Objectis an Object, because it groups a set of Variablesand Objectscontaining information about the Server. The ServerTypeis a complex ObjectType, because the basic structure of the Server Objectshould be well-defined. However, the Server Objectcan be extended by adding Variablesand Objectsin an appropriate structure of the Server Objector its containing Objects.