UA Part 5: Information Model - D.5 Node Definitions

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The HasDescription ReferenceType is a concrete ReferenceType and can be used directly. It is a subtype of NonHierarchicalReferences.

The semantic of this ReferenceType is to reference the DataTypeDescription of a DataTypeEncoding.

The SourceNode of References of this type shall be an Object of the ObjectType DataTypeEncodingType or one of its subtypes.

The TargetNode of this ReferenceType shall be a Variable of the VariableType DataTypeDescriptionType or one of its subtypes.

Its representation in the AddressSpace is specified in Table D.1.

Table D.1 – HasDescription ReferenceType

Attributes	Value
BrowseName	HasDescription
InverseName	DescriptionOf
Symmetric	False
IsAbstract	False
References	NodeClass	BrowseName	Comment

D.5.2 DataTypeDictionaryType

The DataTypeDictionaryType VariableType is used as the type for the DataTypeDictionaries. It is formally defined in Table D.2.

Table D.2 – DataTypeDictionaryType Definition

Attribute		Value
BrowseName		DataTypeDictionaryType
IsAbstract		False
ValueRank		−1 (−1 = Scalar)
DataType		ByteString
References	NodeClass		BrowseName	DataType	TypeDefinition	ModellingRule
Subtype of the BaseDataVariableType defined in 7.4.
HasProperty	Variable		DataTypeVersion	String	PropertyType	Optional
HasProperty	Variable		NamespaceUri	String	PropertyType	Optional
HasProperty	Variable		Deprecated	Boolean	Property Type	Optional

The Property DataTypeVersion is explained in D.3.

The NamespaceUri is the URI for the namespace described by the Value Attribute of the DataTypeDictionary. This is not always the same as the NamespaceUri of the DataType NodeId.

The Deprecated Property is used to indicate that all of the DataType definitions represented by the DataTypeDictionaryType are available through a DataTypeDefinition Attribute. Servers that provide DataType definitions as a DataTypeDefinition Attribute and through a DataTypeDictionaryType shall expose this Property.

D.5.3 DataTypeDescriptionType

The DataTypeDescriptionType VariableType is used as the type for the DataTypeDescriptions. It is formally defined in Table D.3.

Table D.3 – DataTypeDescriptionType Definition

Attribute		Value
BrowseName		DataTypeDescriptionType
IsAbstract		False
ValueRank		-1 (-1 = Scalar)
DataType		String
References	NodeClass		BrowseName	DataType	TypeDefinition	ModellingRule
Subtype of the BaseDataVariableType defined in 7.4.
HasProperty	Variable		DataTypeVersion	String	PropertyType	Optional
HasProperty	Variable		DictionaryFragment	ByteString	PropertyType	Optional

The Properties DataTypeVersion and DictionaryFragment are explained in D.3.

D.5.4 DataTypeSystemType

The DataTypeSystems ObjectType is used as type for the DataTypeSystems. There are no References specified for this ObjectType. It is formally defined in Table D.4.

Table D.4 – DataTypeSystemType Definition

Attribute			Value
BrowseName			DataTypeSystemType
IsAbstract			False
References	NodeClass	BrowseName		DataType	TypeDefinition	ModellingRule
Subtype of the BaseObjectType defined in 6.2.

D.5.5 OPC Binary

OPC Binary is a standard DataTypeSystem defined by OPC. It is represented in the AddressSpace by an Object Node. The OPC Binary DataTypeSystem is defined in OPC 10000-3. OPC Binary uses XML to describe complex binary data values. The “OPC Binary” Object is formally defined in Table D.5.

Table D.5 – OPC Binary Definition

Attribute	Value
BrowseName	OPC Binary
References		NodeClass	BrowseName	Comment
HasTypeDefinition		ObjectType	DataTypeSystemType	Defined in D.5.4

D.5.6 XML Schema

XML Schema is a standard DataTypeSystem defined by the W3C. It is represented in the AddressSpace by an Object Node. XML Schema documents are XML documents whose xmlns attribute in the first line is:

schema xmlns =http://www.w3.org/1999/XMLSchema

The “XML Schema” Object is formally defined in Table D.6.

Table D.6 – XML Schema Definition

Attribute		Value
BrowseName		XML Schema
References	NodeClass		BrowseName	Comment
HasTypeDefinition	ObjectType		DataTypeSystemType	Defined in D.5.4