A stacklight is used to visually or acoustically indicate the state or a specific event of an automation component. It is widely used in various areas of industrial automation. In Figure 1, examples of stacklights are given. They can vary in colours they display or acoustical signals they produce.

Figure 1 Examples of stacklights

This section defines base modelling constructs to represent stacklights in an OPC UA Information Model. It does not define the relations to the triggers of a specific visualization or acoustic signal, like an Alarm or a specific Value of a Variable.