Clients use the browse Services of the View Service Set to navigate through the AddressSpace to discover the HistoricalNodes and their characteristics. These Services provide the most current information about the AddressSpace. It is possible and probable that the AddressSpace of a Server will change over time (i.e. TypeDefinitions may change; NodeIds may be modified, added or deleted).
Server developers and administrators need to be aware that modifying the AddressSpace may impact a Client’s ability to access historical information. If the history for a HistoricalNode is still required, but the HistoricalNode is no longer historized, then the Object should be maintained in the AddressSpace, with the appropriate AccessLevel Attribute and Historizing Attribute settings (see OPC 10000-3 for details on access levels).