Using the MachineryBuildingBlocks Object may lead to several paths to the same Node in a TypeDefinition (see for example Figure 7). When instantiating such a TypeDefinition it is recommended to keep this approach and let several References lead to the same Node, rather than duplicating the Node. In Figure 8, an example is given. The X:SpecificMachineType is referencing the 2:Identification Object directly and from the MachineryBuildingBlocks Object. The Object Machine123 of X:SpecificMachineType is doing the same, and not duplicating the 2:Identification Object (which would be an allowed instantiation, see OPC 10000-3). This avoids unnecessary Nodes and potentially inconsistent data, like in Object Machine124.

Figure 8 – Example of Instantiation without duplicates