What is the benefit of the VariableTypes PublisherCapabilitiesType, SubscriberCapabilitiesType, ServerAddressType, SecurityKeyServerAddressType?

It makes the implementation much more complicated and there is no benefit for clients since they need to handle complex types anyhow since they are contained in the sub-variables.

Arguments for VariableTypes in addition to DataTypes:

• Support simple clients that are not able to display complex types (not relevant since the sub-variables still use complex types)
• Monitor single fields of a structure - not relevant, the information is not frequently changing
• Write single elements of a structure - not relevant since most of the data is readonly or is changed only by one client (locked)

I would strongly recommend to delete the VariableTypes and to define only the DataTypes.