Information Model developers define standard AddressSpaceswhich are implemented by many Servers. There is a need for a standard syntax that Information Model developers can use to formally define their models in a form that can be read by a computer program. Annex Fdefines an XML-based schema for this purpose.

The XML Schema released with this version of the standards can be found here:

http://www.opcfoundation.org/UA/schemas/1.05/UANodeSet.xsd

NOTE The latest file that is compatible with this version of the standards can be found here:

http://opcfoundation.org/UA/2011/03/UANodeSet.xsd

The schema document is the formal definition. The description in Annex Fonly discusses details of the semantics that cannot be captured in the schema document. Types which are self-describing are not discussed.

This schema can also be used to serialize (i.e. import or export) an arbitrary set of Nodesin the Server Address Space. This serialized form can be used to save Serverstate for use by the Serverlater or to exchange with other applications (e.g. to support offline configuration by a Client).

This schema only defines a way to represent the structure of Nodes. It is not intended to represent the numerous semantic rules which are defined in other parts of the OPC UA specification. Consumers of data serialized with this schema need to handle inputs that conform to the schema, however, do not conform to the OPC UA specification because of one or more semantic rule violations.

There are cases where an Information Modeldefines Nodessuch as standard Propertieswhich can be attached to many different Nodes. These Nodesare represented in the UANodeSetas Nodeswhich are not a target of any reference that would make them visible in an AddressSpace.

The tables defining the DataTypesin the specification have field names starting with a lowercase letter. The first letter shall be converted to upper case when the field names are formally defined in a UANodeSet.

Every UANodeSetthat defines DataTypeshas associated schema files that define how to serialize the DataTypesusing the UA Binary Encoding (5.2) and the UA XML Encoding (5.3). The XML schema file may be referenced by the UANodeSetif it includes Variable Values(F.8) for one or more of the DataTypesdefined in the UANodeSet. The namespace URI assigned to the XML schema is set by the tool that generated it. The URI for the XML schema for OPC UA DataTypesis http://opcfoundation.org/UA/2008/02/Types.xsd.