## 4 Technologies to Support Contextualization
### Building and Interconnecting Formal Models  
If technologies are to support operators' understanding of contextual constraints based on the relations in a system, these relations need to be modelled. To this end, an automated integration and use of lifecycle data is needed. This already starts during the _engineering stage_ of a plant. First, individual plant equipment must be described. What technical specifications does it have? What can it do? How can it be connected to other  
Figure 1: Overview of technologies. Yellow boxes represent functional requirements, green boxes represent technical concepts, and purple boxes represent specific technologies. Concepts and technologies are linked to both the functional requirements (grey arrows) and to each other (black bold lines). equipment? In the process industries, various exchange formats for this purpose (e.g., DEXPI, NE150, NE159, and NE100) enable different views on a plant for the respective engineering phase [118]. Nevertheless, some important aspects are not formally modelled in contemporary plants (e.g., issues concerning functional requirements). Furthermore, the concept of module type packages (MTP) was proposed for easy integration into higher-level systems to standardize access to process variables and services of autonomous process units [119]. For instance, a module that is capable of tempering and mixing must know about the current state of these functions, and it must communicate this information in a certain manner. Standardized descriptions such as MTP make it easy to integrate the process data of modules from different vendors and provide operators with integrated and consistent information about the module assembly. However, as the interface description does not follow a semantic information model, capability descriptions are not part of the MTP. This requires additional non-standardized documents in the plant design phase to describe services and process variables. Planning data that are based on formal descriptions such as DEXPI (see above) cannot only describe individual components of a plant but also specify how equipment or functions are _connected_. This requires descriptions on different levels of abstraction such as specific physical connections (e.g., pipe and instrumentation diagrams) or abstract sequences of unit operations (e.g., process flow diagrams). For the definition of single assets (e.g., pump or motor), the concept of an asset administration shell (AAS) was introduced by the Industry 4.0 initiative. This AAS accompanies an asset in all phases of its life, from planning to decommissioning, and keeps all digital information available. Standardized descriptions exist, especially in the form of OPC UA Companion standards (see below) [120]. Such descriptions are not limited to individual machines but should include different production steps within a plant. This knowledge can be used to draw conclusions. For instance, if a buffer is located in front of the fourth of four parallel packaging machines, it follows that problems resulting from the buffer (e.g., warm chocolate due to long storage duration) can only affect the fourth machine but not the three previous ones. As easy as this conclusion is for humans, it must be formalized to make it available for use in operator support systems. This formal modelling can be realized with the help of _ontologies_[121]. However, modelling the physical setup only is a first step, and additional models are needed. In the process industries, the required models are summarized in the _products-processes-resources_ (PPR) framework. Process models contain information about the current and future state and behavior of the chemical process, process relations (e.g., thermodynamic, chemical), suitable operation ranges, or safety-related issues. Product models refer to raw materials, intermediates, waste, and end products. They encompass factors such as the physical properties of pure substances, nonlinear interactions in mixtures, product specifications, and risks for human health or the environment.