3 Terms, definitions and conventions ToC Previous Next

3.4 Conventions used in this document ToC Previous Next

3.4.1 Conventions for Node descriptions ToC Previous Next

Node definitions are specified using tables (see Table 2).

Attributes are defined by providing the Attribute name and a value, or a description of the value.

References are defined by providing the ReferenceType name, the BrowseName of the TargetNode and its NodeClass.

  • If the TargetNode is a component of the Node being defined in the table the Attributes of the composed Node are defined in the same row of the table.
  • The DataType is 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 ArrayDimensions is 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 ArrayDimensions can be omitted. If no brackets are provided, it identifies a scalar DataType and the ValueRank is set to the corresponding value. In addition, ArrayDimensions is 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 ValueRank is set to the corresponding value and the ArrayDimensions is set to null or is omitted. Examples are given in Table 1.

Table 1 — Examples of DataTypes

Notation DataType ValueRank ArrayDimensions Description
Int32 Int32 -1 omitted or null A scalar Int32.
Int32[] Int32 1 omitted or {0} Single-dimensional array of Int32 with an unknown size.
Int32[][] Int32 2 omitted or {0,0} Two-dimensional array of Int32 with unknown sizes for both dimensions.
Int32[3][] 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.
Int32[5][3] 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.
Int32{Any} Int32 -2 omitted or null An Int32 where it is unknown if it is scalar or array with any number of dimensions.
Int32{ScalarOrOneDimension} Int32 -3 omitted or null An Int32 where it is either a single-dimensional array or a scalar.
  • The TypeDefinition is specified for Objects and Variables.
  • The TypeDefinition column specifies a symbolic name for a NodeId, i.e. the specified Node points with a HasTypeDefinition Reference to the corresponding Node.
  • The ModellingRule of the referenced component is provided by specifying the symbolic name of the rule in the ModellingRule column. In the AddressSpace, the Node shall use a HasModellingRule Reference to point to the corresponding ModellingRule Object. If the NodeId of a DataType is provided, the symbolic name of the Node representing the DataType shall be used.

Nodes of all other NodeClasses cannot be defined in the same table; therefore only the used ReferenceType, their NodeClass and their BrowseName are specified. A reference to another part of this document points to their definition.

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

Table 2 — Type Definition Table

Attribute Value
Attribute name Attribute value. If it is an optional Attribute that is not set “–“ will be used.
   
References NodeClass BrowseName DataType TypeDefinition ModellingRule
ReferenceType   name NodeClass   of the TargetNode. BrowseName   of the target Node. If the Reference is to be instantiated by the server, then the value of the target Node’s BrowseName is “–“. DataType of the referenced Node, only applicable for Variables. TypeDefinition   of the referenced Node, only applicable for Variables and Objects. Referenced ModellingRule of the referenced Node and AccessLevel of the Node if it is a Variable.
NOTE Notes referencing footnotes of the table content.          

In addition, the following abbreviations defined in Table 3 are used in the ModellingRule column in the tables for the definition of ObjectTypes.

Table 3 — Abbreviations for ModellingRule and AccessLevel

Abbreviation Description
O Modelling Rule Optional
M Modelling Rule Mandatory
OP Modelling Rule OptionalPlaceholder
MP Modelling Rule MandatoryPlaceholder
R AccessLevel Readable
W AccessLevel Writable
RW AccessLevel Readable and Writable

As example for the use of the Modelling Rule Mandatory and AccessLevel Readable and Writable variables, the abbreviation is “M, RW”.

Components of Nodes can be complex that is containing components by themselves. The TypeDefinition, NodeClass, DataType and ModellingRule can be derived from the type definitions, and the symbolic name can be created as defined in 3.4.3.1. Therefore, those containing components are not explicitly specified; they are implicitly specified by the type definitions.

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