For systems that are large and complex, engineering is often done in multiple tools and by multiple individuals. The separate configurations are required to work together, but resolving the references between these different configurations can be a significant task. A common solution to simplify this task is a naming convention for the items that are being referenced. Providing an automatic lookup capability for these names would greatly simplify configuration. Each system can specify its own names and configurations can be built to just use the names, without having to know the exact address of the items. The exact address would include the address of the Server, the address of the tag in the Server, the required protocol for connecting to the Server, security settings etc. OPC UA defines a GDS that can provide information about what Servers are available in a system and how to connect to them, but it does not currently provide information about the tags that are available in a given Server.
In a system where many smaller Servers exist and these Servers might be dynamic, in that new Servers can appear and disappear. Configuration might move between Servers. The automatic resolution of where a specific piece of information is located would greatly simplify these systems.
Much like the previous use case, a cloud-based system, where Servers can be spun up in a new cloud system or adjusted and split based on loading to multiple Servers. The automatic resolution of where a specific piece of information is located would greatly simplify these systems.
In systems where many simple devices exist, any given simple device might not have the ability to provide name resolution, yet these systems can be much like systems in one of the previous use cases. In a system such as this an aggregating Server might exist, where the aggregating Server would provide the names as well as the lookup for the underlying Server. This aggregating Server might also provide other functionality such as aggregation of values, but it might only provide the name definitions and resolutions. The underlying Server might have no knowledge of the name.