The IrdiDictionaryEntryType defined in Table 3 is used to represent dictionary entries that use standardized semantic identifiers that conform with International Registration Data Identifiers (IRDI) defined in ISO/IEC 11179-6.

Standardized semantic identifiers are locale independent strings typically specified in international standards like IEC CDD (Common Data Dictionary) (IEC 61987). In order to avoid conflict with various name spaces in these identifiers, the registration authority identifier part of the string used shall be based on ISO 29002-5.

Figure 2 shows the general structure and syntax defined by ISO/IEC 11179-6, ISO 29002-5 and ISO/IEC 6523.

Figure 2 – IRDI overview

Examples for IRDI strings defined by standards using the IRDI format

IEC CDD 0112/2//a/61360_4#AAE867#001 Proximity switch, Output current

ISO 55980112-1-a-18582#KAA802#s Pneumatic value

ECLASS 0173/1///#02-8AD792#s Inductive distance sensor, Design of analog output

Table 3 – IrdiDictionaryEntryType Definition

Attribute	Value
BrowseName	IrdiDictionaryEntryType
IsAbstract	False
References	NodeClass	BrowseName	DataType / TypeDefinition	ModellingRule
Subtype of the DictionaryEntryType defined in OPC 10000-5.
Conformance Units
Address Space Dictionary IRDI

The identifier in the respective external dictionary shall be a unique string. This identifier is used for the NodeId and the BrowseName Attributes of instances of the DictionaryEntryType. The IdentifierType of the NodeId shall be STRING_1 with the identifier from the external dictionary as the value.

The namespace “http://opcfoundation.org/UA/Dictionary/IRDI” shall be used for instance of the IrdiDictionaryEntryType. Subtypes may define different namespaces.

The identifier shall be immutable; meaning that it shall not be reassigned to a different dictionary entry within the scope of the namespace in future versions. Data dictionaries may be publicly defined by standard bodies such as IEC or proprietary (e.g. vendor-specific dictionaries).