In shortA Unified Namespace (UNS) is an architectural approach that publishes a plant’s current state and events in a single hierarchical namespace, usually implemented with an MQTT broker.
In a UNS, systems publish to and read from a shared namespace instead of connecting point to point. The namespace is usually organised in an ISA-95-inspired hierarchy such as enterprise/site/area/line/cell/metric.
This approach reduces the number of connections and makes it easier to add new consumers, but its success depends on careful design of naming and the data contract. The UNS article explains the principles; the MQTT topic builder generates sample topics.