Overview
ISO/IEC 8824-2:2021 - part of the Abstract Syntax Notation One (ASN.1) family - defines a formal information object specification notation. Published jointly with ITU-T as X.681 (02/2021), this sixth edition standardizes how to specify information object classes, information objects, and information object sets in ASN.1. It is intended for protocol and data modelling where sets of extensible, named objects (for example, operations or attributes) must be referenced, extended, and used as ASN.1 types.
Key topics and technical requirements
- Information object class definition: notation for naming fields, their forms (type fields, fixed/variable value fields, value-set fields, object and object-set fields), optionality, defaults, and the identifier field.
- Information object and object set assignment: syntax to define and assign individual objects and collections (object sets) of a class.
- Identifier uniqueness: values of an identifier field (when supplied) must be unique within an information object set as defined by the standard.
- Object class field type: allows an ASN.1 type to reference a named field of a named object class - enabling types derived from object definitions.
- InformationFromObjects: notation to extract data from specified objects or object sets (useful for parameterized protocols).
- Object set extension marker: rules for signaling that an object set may be extended dynamically; implementers must support dynamic addition/removal mechanisms where extension markers appear.
- Normative annexes:
- Annex A defines the widely used TYPE-IDENTIFIER object class.
- Annex B covers abstract syntax definitions.
- Annex C defines the INSTANCE OF (instance-of) type.
- Annexes D–F provide examples, a tutorial on object set extension, and a notation summary.
Practical applications and users
Who benefits:
- Protocol designers and architects who need to model extensible operations, attributes, or managed objects.
- Telecommunications and network-management implementers requiring stable, referable object definitions.
- ASN.1 tool vendors (compilers, validators) that must parse and enforce object-class semantics and extension rules.
- Standards bodies that publish profiles of operations or attributes for interoperable systems.
Common uses:
- Defining operation sets for remote operation services, directory attribute schemas, and parameterizable protocol specifications.
- Creating ASN.1 types that reference fields of object classes, enabling reusable, extensible data models.
- Supporting dynamic object set extension in systems where managed object sets evolve at runtime.
Related standards
Keywords: ISO/IEC 8824-2:2021, ASN.1, information object specification, information object class, object set extension, TYPE-IDENTIFIER, INSTANCE OF, InformationFromObjects.