Part 11 recognizes that it is a common configuration that there will be a specialized OPC UA Server that provides historical access to data.

The reality of that is that you have 1 server that has the capability of Realtime data updates, and probably a full address space. And another server that has a scoped down set of nodes that may or may not be organized into any particular meaningful address space.

What I think is missing is a relationship type that can be used by these 2 servers that allow them to point to each others nodes with the semantic meaning the target of this relationship is a node that can be used in the historical read services and its has the same semantic meaning as the source node of the relationship, and if its an extended nodeID on another server, you need to call those historical read services on that external OPC UA Server. The inverse of this relationship would also be used by the historical server to indicate an extended nodeID with the semantic meaning, this other node provides the realtime values of this historizing node, and will likely provide more fidelity for the realtime values, and that target node has the same semantic meaning as the source node.

I think a potential browse names for this relationship is HasHistoricalData, and the inverse name would be HasRealtimeData.