OfflineEngineering is an essential element for an automation system's development, commissioning, operation, and maintenance phases. By allowing the user to understand the automation system's operation before deploying the system in physical hardware, the user can be assured the system will perform up to the user's expectations once the physical system is in place. Once the system is commissioned, the user can simulate changes and updates (e.g., using a digital twin) before changing the physical system. OfflineEngineeringsignificantly increases efficiency during the commissioning phase when deploying multiple instances of the same system.

The UAFX OfflineEngineering Specification, OPC 10000-83, defines a standardised archive file called a Descriptorfor provisioning and sharing the information required for OfflineEngineering. The contents of a Descriptor(see OPC 10000-83) is a structured set of documents describing the functionality, capabilities, and configuration of the AutomationComponents. Descriptorsmay also contain supporting documentation such as user manuals and drawings.