Nodedefinitions are specified using tables (see Table 2).

Attributesare defined by providing the Attributename and a value, or a description of the value.

Referencesare defined by providing the ReferenceTypename, the BrowseNameof the TargetNodeand its NodeClass.

  • If the TargetNodeis a component of the Nodebeing defined in the table the Attributesof the composed Nodeare defined in the same row of the table.
  • The DataTypeis only specified for Variables; “[<number>]” indicates a single-dimensional array, for multi-dimensional arrays the expression is repeated for each dimension (e.g. [2][3] for a two-dimensional array). For all arrays the ArrayDimensionsis set as identified by <number> values. If no <number> is set, the corresponding dimension is set to 0, indicating an unknown size. If no number is provided at all the ArrayDimensionscan be omitted. If no brackets are provided, it identifies a scalar DataTypeand the ValueRankis set to the corresponding value (see OPC 10000-3). In addition, ArrayDimensionsis set to null or is omitted. If it can be Any or ScalarOrOneDimension, the value is put into “{<value>}”, so either “{Any}” or “{ScalarOrOneDimension}” and the ValueRankis set to the corresponding value (see OPC 10000-3) and the ArrayDimensionsis set to null or is omitted. Examples are given in Table 1.

Table 1– Examples of DataTypes

Notation

DataType

ValueRank

ArrayDimensions

Description

0:Int32

0:Int32

-1

omitted or null

A scalar Int32.

0:Int32[]

0:Int32

1

omitted or {0}

Single-dimensional array of Int32 with an unknown size.

0:Int32[][]

0:Int32

2

omitted or {0,0}

Two-dimensional array of Int32 with unknown sizes for both dimensions.

0:Int32[3][]

0:Int32

2

{3,0}

Two-dimensional array of Int32 with a size of 3 for the first dimension and an unknown size for the second dimension.

0:Int32[5][3]

0:Int32

2

{5,3}

Two-dimensional array of Int32 with a size of 5 for the first dimension and a size of 3 for the second dimension.

0:Int32{Any}

0:Int32

-2

omitted or null

An Int32 where it is unknown if it is scalar or array with any number of dimensions.

0:Int32{ScalarOrOneDimension}

0:Int32

-3

omitted or null

An Int32 where it is either a single-dimensional array or a scalar.

If the NodeIdof a DataTypeis provided, the symbolic name of the Noderepresenting the DataTypeshall be used.

Note that if a symbolic name of a different namespace is used, it is prefixed by the NamespaceIndex(see 3.3.2.2).

Nodesof all other NodeClassescannot be defined in the same table; therefore, only the used ReferenceType, their NodeClassand their BrowseNameare specified. A reference to another part of this document points to their definition.

Table 2illustrates the table. If no components are provided, the DataType, TypeDefinition and Other columns may be omitted and only a Comment column is introduced to point to the Nodedefinition.

Table 2– Type Definition Table

Attribute

Value

Attribute name

Attribute value. If it is an optional Attribute that is not set "--" is used.

References

NodeClass

BrowseName

DataType

TypeDefinition

Other

ReferenceTypename

NodeClassof the target Node.

BrowseNameof the target Node.

DataType of the referenced Node, only applicable for Variables.

TypeDefinitionof the referenced Node, only applicable for Variablesand Objects.

Additional characteristics of the TargetNodesuch as the ModellingRuleor AccessLevel.

NOTE Notes referencing footnotes of the table content.

Components of Nodescan be complex that is containing components by themselves. The TypeDefinition, NodeClassand DataType can be derived from the type definitions, and the symbolic name can be created as defined in 3.3.3.1. Therefore, those containing components are not explicitly specified; they are implicitly specified by the type definitions.

The Other column defines additional characteristics of the Node. Examples of characteristics that can appear in this column are show in Table 3.

Table 3– Examples of Other Characteristics

Name

Short Name

Description

0:Mandatory

M

The Nodehas the Mandatory ModellingRule.

0:Optional

O

The Nodehas the Optional ModellingRule.

0:MandatoryPlaceholder

MP

The Nodehas the MandatoryPlaceholder ModellingRule.

0:OptionalPlaceholder

OP

The Nodehas the OptionalPlaceholder ModellingRule.

ReadOnly

RO

The Node AccessLevelhas the CurrentReadbit set but not the CurrentWritebit.

ReadWrite

RW

The Node AccessLevelhas the CurrentReadand CurrentWritebits set.

WriteOnly

WO

The Node AccessLevelhas the CurrentWritebit set but not the CurrentReadbit.

If multiple characteristics are defined they are separated by commas. The name or the short name may be used.

To provide information about additional References, the format as shown in Table 4is used.

Table 4– <some>Type Additional References

SourceBrowsePath

Reference Type

Is Forward

TargetBrowsePath

SourceBrowsePath is always relative to the TypeDefinition. Multiple elements are defined as separate rows of a nested table.

ReferenceTypename

True = forward Reference.

TargetBrowsePath points to another Node, which can be a well-known instance or a TypeDefinition. You can use BrowsePathshere as well, which is either relative to the TypeDefinitionor absolute.

If absolute, the first entry needs to refer to a type or well-known instance, uniquely identified within a namespace by the BrowseName.

Referencescan be to any other Node.

To provide information about sub-components, the format as shown in Table 5is used.

Table 5– <some>Type Additional Subcomponents

BrowsePath

References

NodeClass

BrowseName

DataType

TypeDefinition

Others

BrowsePath is always relative to the TypeDefinition. Multiple elements are defined as separate rows of a nested table

NOTE Same as for Table 2

The type definition table provides columns to specify the values for required Node Attributesfor InstanceDeclarations. To provide information about additional Attributes, the format as shown in Table 6is used.

Table 6– <some>Type Attribute values for child Nodes

BrowsePath

<Attribute name> Attribute

BrowsePath is always relative to the TypeDefinition. Multiple elements are defined as separate rows of a nested table

The values of attributes are converted to text by adapting the reversible JSON encoding rules defined in OPC 10000-6.

If the JSON encoding of a value is a JSON string or a JSON number then that value is entered in the value field. Double quotes are not included.

If the DataType includes a NamespaceIndex (QualifiedNames, NodeIds or ExpandedNodeIds) then the notation used for BrowseNames is used.

If the value is an Enumeration the name of the enumeration value is entered.

If the value is a Structure then a sequence of name and value pairs is entered. Each pair is followed by a newline. The name is followed by a colon. The names are the names of the fields in the DataTypeDefinition.

If the value is an array of non-structures then a sequence of values is entered where each value is followed by a newline.

If the value is an array of Structures or a Structure with fields that are arrays or with nested Structures then the complete JSON array or JSON object is entered. Double quotes are not included.

There can be multiple columns to define more than one Attribute.

The NodeIdsof all Nodesdescribed in this standard are only symbolic names. Annex Adefines the actual NodeIds.

The symbolic name of each Nodedefined in this document is its BrowseName, or, when it is part of another Node, the BrowseNameof the other Node, a “.”, and the BrowseNameof itself. In this case “part of” means that the whole has a HasPropertyor HasComponent Referenceto its part. Since all Nodesnot being part of another Nodehave a unique name in this document, the symbolic name is unique.

The NamespaceUrifor all NodeIdsdefined in this document is defined in Annex A. The NamespaceIndexfor this NamespaceUriis vendor-specific and depends on the position of the NamespaceUriin the server namespace table.

Note that this document not only defines concrete Nodes, but also requires that some Nodesshall be generated, for example one for each Sessionrunning on the Server. The NodeIdsof those Nodesare Server-specific, including the namespace. But the NamespaceIndexof those Nodescannot be the NamespaceIndexused for the Nodesdefined in this document, because they are not defined by this document but generated by the Server.

The text part of the BrowseNamesfor all Nodesdefined in this document is specified in the tables defining the Nodes. The NamespaceUrifor all BrowseNamesdefined in this document is defined in 16.2.

For InstanceDeclarationsof NodeClass Objectand Variablethat are placeholders (OptionalPlaceholderand MandatoryPlaceholder ModellingRule), the BrowseNameand the DisplayNameare enclosed in angle brackets (<>) as recommended in OPC 10000-3. If the BrowseNameis not defined by this document, a namespace index prefix is added to the BrowseName(e.g., prefix '0' leading to ‘0:EngineeringUnits’ or prefix '2' leading to ‘2:DeviceRevision’). This is typically necessary if a Propertyof another specification is overwritten or used in the OPC UA types defined in this document. Table 58provides a list of namespaces and their indexes as used in this document.

The Attributesof Nodes, their DataTypesand descriptions are defined in OPC 10000-3. Attributes not marked as optional are mandatory and shall be provided by a Server. The following tables define if the Attributevalue is defined by this document or if it is server-specific.

For all Nodesspecified in this document, the Attributesnamed in Table 7shall be set as specified in the table.

Table 7– Common Node Attributes

Attribute

Value

DisplayName

The DisplayNameis a LocalizedText. Each Servershall provide the DisplayNameidentical to the BrowseNameof the Nodefor the LocaleId“en”. Whether the server provides translated names for other LocaleIdsare server-specific.

Description

Optionally a server-specific description is provided.

NodeClass

Shall reflect the NodeClassof the Node.

NodeId

The NodeIdis described by BrowseNamesas defined in 3.3.2.1.

WriteMask

Optionally the WriteMask Attributecan be provided. If the WriteMask Attributeis provided, it shall set all non-server-specific Attributesto not writable. For example, the Description Attributemay be set to writable since a Servermay provide a server-specific description for the Node. The NodeIdshall not be writable, because it is defined for each Nodein this document.

UserWriteMask

Optionally the UserWriteMask Attributecan be provided. The same rules as for the WriteMask Attributeapply.

RolePermissions

Optionally server-specific role permissions can be provided.

UserRolePermissions

Optionally the role permissions of the current Session can be provided. The value is server-specific and depends on the RolePermissions Attribute(if provided) and the current Session.

AccessRestrictions

Optionally server-specific access restrictions can be provided.

For all Objectsspecified in this document, the Attributesnamed in Table 8shall be set as specified in the Table 8. The definitions for the Attributescan be found in OPC 10000-3.

Table 8– Common Object Attributes

Attribute

Value

EventNotifier

Whether the Nodecan be used to subscribe to Eventsor not is server-specific.

For all Variablesspecified in this document, the Attributesnamed in Table 9shall be set as specified in the table. The definitions for the Attributescan be found in OPC 10000-3.

Table 9– Common Variable Attributes

Attribute

Value

MinimumSamplingInterval

Optionally, a server-specific minimum sampling interval is provided.

AccessLevel

The access level for Variablesused for type definitions is server-specific, for all other Variablesdefined in this document, the access level shall allow reading; other settings are server-specific.

UserAccessLevel

The value for the UserAccessLevel Attributeis server-specific. It is assumed that all Variablescan be accessed by at least one user.

Value

For Variablesused as InstanceDeclarations,the value is server-specific; otherwise it shall represent the value described in the text.

ArrayDimensions

If the ValueRankdoes not identify an array of a specific dimension (i.e. ValueRank<= 0) the ArrayDimensionscan either be set to null or the Attributeis missing. This behaviour is server-specific.

If the ValueRankspecifies an array of a specific dimension (i.e. ValueRank> 0) then the ArrayDimensions Attributeshall be specified in the table defining the Variable.

Historizing

The value for the Historizing Attributeis server-specific.

AccessLevelEx

If the AccessLevelEx Attributeis provided, it shall have the bits 8, 9, and 10 set to 0, meaning that read and write operations on an individual Variableare atomic, and arrays can be partly written.

For all VariableTypesspecified in this document, the Attributesnamed in Table 10shall be set as specified in the table. The definitions for the Attributescan be found in OPC 10000-3.

Table 10– Common VariableType Attributes

Attributes

Value

Value

Optionally a server-specific default value can be provided.

ArrayDimensions

If the ValueRankdoes not identify an array of a specific dimension (i.e. ValueRank<= 0) the ArrayDimensionscan either be set to null or the Attributeis missing. This behaviour is server-specific.

If the ValueRankspecifies an array of a specific dimension (i.e. ValueRank> 0) then the ArrayDimensions Attributeshall be specified in the table defining the VariableType.

For all Methodsspecified in this document, the Attributesnamed in Table 11shall be set as specified in the table. The definitions for the Attributescan be found in OPC 10000-3.

Table 11– Common Method Attributes

Attributes

Value

Executable

All Methodsdefined in this document shall be executable (Executable Attributeset to “True”), unless it is defined differently in the Methoddefinition.

UserExecutable

The value of the UserExecutable Attributeis server-specific. It is assumed that all Methodscan be executed by at least one user.