Annex A points out some general considerations on how the Address Space Model can be used. Annex A is for information only, that is, each Server vendor can model its data in the appropriate way that fits its needs. However, it gives some hints the Server vendor may consider.
Typically OPC UA Servers will offer data provided by an underlying system like a device, a configuration database, an OPC COM Server, etc. Therefore the modelling of the data depends on the model of the underlying system as well as the requirements of the Clients accessing the OPC UA Server. It is also expected that companion specifications will be developed on top of OPC UA with additional rules on how to model the data. However, the remainder of Annex A will give some general considerations about the different concepts of OPC UA to model data and when they should be used, and when not.