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Glossary

AddIn​

A reusable Object attached to a type, declared through addIns:. Carries a DefaultInstanceBrowseName so every instance names it the same way.

Address space​

The graph of nodes and references an OPC UA server exposes. Browsing it is how a client discovers what a server offers.

BrowseName​

A node's stable, human-facing name, qualified by namespace — di:ParameterSet. Clients are written against BrowseNames, not NodeIds.

Companion specification​

A published set of OPC UA types for a domain — Devices (DI), Machinery, Robotics. Standardised so that tooling written once works across vendors. See Namespaces.

Component​

A child attached by HasComponent — the substance of a type. In the DSL, components:.

DataType​

The type of a Variable's value: a built-in like ua:Double, an enumeration, or a structure. See Data types.

Diagnostic​

A message from the compiler carrying a stable DSL-… code. See the catalogue.

Engineering unit​

The unit of a measured value, from UNECE Recommendation 20. Written as the symbol — °C, not "degree Celsius".

Instance​

A concrete Object or Variable in the address space, pointing at a TypeDefinition. In the DSL, instances:.

Interface​

A set of members a type promises to expose, independent of its inheritance — OPC UA's answer to multiple inheritance. See Interfaces.

Modelling rule​

Whether a member appears on every instance (Mandatory) or only when requested (Optional). promotedToMandatory: turns an inherited optional into a mandatory one.

Namespace​

A URI identifying who defined a set of nodes. Your model defines one (namespaceUri) and uses others (namespaces:, imports:).

NodeId​

A node's machine-facing identifier, unique within a server. Assigned by the generator, kept stable by the symbols file. You do not write these.

NodeSet2​

The standard XML interchange format for an OPC UA information model, defined by OPC 10000-6. What the modeller produces and what every server consumes.

Property​

A child attached by HasProperty — metadata about a node rather than data from the process. Serial number, engineering range.

Reference​

A typed edge between two nodes. HasComponent, HasProperty and HasSubtype are the ones you meet most.

State machine​

A type derived from FiniteStateMachineType, defined by its states and the transitions between them. See State machines.

Symbols file​

symbols.csv — the BrowseName to NodeId mapping. Both an output and an input: committing it is what keeps NodeIds stable across regenerations. See the pipeline.

TypeDefinition​

The type an instance points at, describing its members. ObjectType for Objects, VariableType for Variables.

YAML DSL​

The language these docs describe: a compact way to write an OPC UA information model that compiles to NodeSet2. Formally specified in the DSL specification.