The OPC UA specification is organized as a multi-part series to provide a modular and extensible framework. This structure allows for focused development and maintenance of specific aspects of the technology, while ensuring overall coherence. The parts are broadly categorized into core concepts, information models, services, mappings, profiles, and domain-specific applications. Parts 1 through 5 describe core concepts of OPC UA, therefore, readers are encouraged to read Parts 1 through 5 of the specification before reading the other Parts.