IEC 81346-2-2019 PDF

Full title and description

Industrial systems, installations and equipment and industrial products — Structuring principles and reference designations — Part 2: Classification of objects and codes for classes. This part of IEC 81346 defines classification schemes with standardized object classes and associated letter codes for use in reference designations and for designation of generic types across technical disciplines and industry branches.

Abstract

IEC 81346-2:2019 establishes a three-level classification scheme and provides stable, definition‑based class codes (letter codes) for objects (including systems and system elements) so they can be referenced unambiguously across the lifecycle of systems and products. It is a horizontal publication intended to support reference designation work by technical committees in line with IEC Guide 108. The 2019 edition cancels and replaces the 2009 edition and introduces several technical revisions including alignment with ISO 22274 and ISO 704, clearer definition‑based classes, a three‑level coding approach, and a separate classification scheme for spaces.

General information

• Status: Published.
• Publication date: 2019-06 (published June 2019, IEC publication date 18 June 2019).
• Publisher: International Electrotechnical Commission (IEC), bilingual English/French publication.
• ICS / categories: 01.110 (Technical product documentation), 29.020 (Electrical engineering in general).
• Edition / version: Edition 2.0 (2019).
• Number of pages: 197 pages.

Scope

Specifies classification schemes and letter codes for classes of objects to be used in reference designations and for generic type designation. The schemes are applicable across all technical disciplines and industry branches and are intended for use by designers, documentation specialists and technical committees when preparing standards or systems that require unambiguous object identification. The document focuses on class definitions (based on inherent function) rather than names or examples, and provides rules and examples to support consistent selection and use of class codes.

Key topics and requirements

• Definition‑based class codes (letter codes) for objects to ensure stable, technology‑neutral classification across lifecycles.
• Three‑level classification scheme (three abstraction levels) enabling flexibility for sector or designer-specific needs.
• Alignment of class definitions with ISO principles (ISO 22274 and ISO 704) for terminology and classification.
• Separate classification scheme for spaces (rooms/areas) in addition to equipment/system classes.
• Guidance to apply the classification in reference designation systems (RDS) and to support preparation of related standards per IEC Guide 108.

Typical use and users

Used by system engineers, plant and installation designers, technical documentation authors, maintenance and asset‑management teams, CAD/PLM integrators, and standards committees. Typical applications include creation of reference designation schemes, asset tagging, cross‑discipline documentation, parts and system classification, and sector‑specific extensions of the RDS approach.

Related standards

Part of the 81346 series (structuring principles and reference designations). Closely related and commonly used together are IEC 81346‑1 (Basic rules / structuring principles — edition 2.0, 2022) and sector or domain parts such as ISO/IEC 81346‑10 (Power supply systems, 2022) and ISO 81346‑12 (Construction works and building services, 2018). Earlier application guidance documents (IEC/TR 61346‑3 and IEC 61346‑4) have been withdrawn or superseded as the series evolved.

Keywords

reference designation, classification, object classes, letter codes, RDS, structuring principles, IEC 81346, system documentation, asset identification, ISO alignment

FAQ

Q: What is this standard?

A: IEC 81346‑2:2019 is the part of the IEC/ISO 81346 series that defines classification schemes and letter codes for object classes used in reference designation systems (RDS).

Q: What does it cover?

A: It covers the classification of objects (systems, sub‑systems, components, spaces) and provides standardized letter codes and rules for selecting classes so objects can be referenced unambiguously across documents and lifecycles. The 2019 edition introduced a three‑level scheme, clearer definition‑based classes and a space classification.

Q: Who typically uses it?

A: System and installation designers, technical writers, maintenance and asset managers, PLM/CAD integrators, and standards developers who need consistent reference designations and object classification across disciplines and documentation.

Q: Is it current or superseded?

A: IEC 81346‑2:2019 is the published (second) edition from June 2019 and remains the active Part 2 document; the 81346 series is periodically reviewed and other parts (and new editions) are developed — a draft (IEC/DIS 81346‑2) toward a later edition has been registered in the maintenance cycle. Check national/IEC catalogues for the latest revision activity before assuming a change.

Q: Is it part of a series?

A: Yes — it is part of the ISO/IEC 81346 series (structuring principles and reference designations). The series includes Part 1 (basic rules), Part 2 (this classification part), and several sector‑specific parts (for example Part 10 and Part 12).

Q: What are the key keywords?

A: Reference designation, classification, RDS, letter codes, object classes, structuring principles, system documentation.