Plant Engineering Infobase · Chapter 03 of 14
Plant identification
Identification systems give every component of a plant a unique, machine-readable designation. In CAD, they are automated using property fields and tag formats.
Reference designation according to DIN EN IEC 81346
The DIN EN IEC 81346 series of standards (formerly EN 61346) is the cross-industry basis. It considers an object from three aspects, each with its own prefix:
| Character | Aspect | Question | Example |
|---|---|---|---|
| = | Function | What does the object do? | =A1.WC01 |
| - | Product | What does it consist of? | -GP01 |
| + | Location | Where is it located? | +B01.R12 |
DIN 6779 has been withdrawn in parts 1, 2 and 10 and incorporated into DIN EN IEC 81346 and ISO/TS 81346-10. Individual industry-specific parts are still valid, e.g. DIN 6779-13:2018-01 (replaces the 2003-06 edition) for chemical plants.
KKS – power plant classification system
Since the 1980s, the KKS has identified systems, plant sections and devices in power plants by function, type and location. It is maintained by VGB; the governing standard today is VGB-S-811-01 (8th edition 2018). An identifier has 15 to 17 characters. Letters (A) classify, digits (N) count. The level of detail increases from left to right.
| Breakdown level | 0 | 1 | 2 | 3 |
|---|---|---|---|---|
| Process designation | Overall plant | System | Package unit | Equipment item / signal |
| Installation location designation | Overall plant | Installation unit | Installation location | – |
| Room designation (installation site) | Overall plant | Structure | Room | – |
| Format | A or N | (N)AAANN | AANNN(A) | AANN |
Example: pump of a water spray extinguishing system
| Level | Meaning | Identifier |
|---|---|---|
| 0 | Overall plant: Unit A | =A |
| 1 | System: water spray extinguishing system no. 1 | 0SGC10 |
| 2 | Package unit: pump unit | AP001 |
| 3 | Equipment item: pump | KP01 |
The successor to KKS is RDS-PP (Reference Designation System for Power Plants), based on DIN EN IEC 81346 and now published as ISO/TS 81346-10:2022. The former classification as ISO/TS 16952-10 is obsolete.
Summary based on Wikipedia: Kraftwerk-Kennzeichensystem and Wikipedia: RDS-PP; guideline: VGB-S-811-01
AKS – plant identification for buildings
Many public and private clients require their own plant identification system (AKS), usually for building services and building automation. It is not a standard; the structure and number of characters are defined by the respective client guideline. The cost groups usually refer to DIN 276. A typical structure with 29 characters in 11 levels:
| Level | Contents | Characters |
|---|---|---|
| Plant level (mandatory) | ||
| 1 | Country code | 1 |
| 2 | Location code | 2–6 |
| 3 | Building | 7–9 |
| 4 | Floor level | 10–11 |
| 5 | Documentation status | 12 |
| 6 | Cost group | 13–16 |
| 7 | Sequential number of the system | 17–19 |
| Data point level (only when integrated into building automation) | ||
| 8 | Assembly / equipment item | 20–22 |
| 9 | Separator, sequential no. of equipment item | 23–25 |
| 10 | Measured variable / data point | 26–27 |
| 11 | Sequential no. of the data point | 28–29 |
D-12345-XYZ-01-A-584_101-100-10HS01-CHS-002. If the part up to the documentation status is already in the title block, the remainder is sufficient on the drawing.Identification letters for equipment, valves and piping
Letter codes for equipment are now assigned according to the classes of DIN EN IEC 81346-2 or defined in the operator's project or plant standard. The list belongs on the legend sheet of the P&IDs and in the tag configuration of the CAD project. Pipe identification also includes nominal size, pressure rating, fluid and piping spec.
Related offering
ASEING PlantConfig Pro – identification systems fully set up
Numbering according to DIN EN ISO 10628, AKS, KKS and RDS-PP is available as ready-to-use project templates for AutoCAD P&ID and Plant 3D: field definitions with levels and selection lists, tag formats, automatic annotation, title block according to DIN EN ISO 7200, symbol palettes and check reports.
Company license from €2,490 net plus VAT (tiered by number of Plant 3D users) · 15% less in a package with PlantPlus · individual templates on request
Check and compose identifiers
Check KKS identifiers for the structure of breakdown levels 0 to 3 and explain the letter codes in plain text (excerpt from Wikipedia, with source reference), compose AKS identifiers according to the levels of the client guideline, and form reference designations according to DIN EN IEC 81346 with the prefixes for function, product and location – right in your browser.
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Standards status for this page 9 standards · researched September 2026
| Standard | Contents | Current edition | Replaced / successor |
|---|---|---|---|
| DIN EN IEC 81346-1 | Structuring principles and reference designations – Part 1: Basic rules | DIN EN IEC 81346-1:2024-07 | replaces DIN EN 81346-1:2010-05 |
| DIN EN IEC 81346-2 | Structuring principles and reference designation – Part 2: Classification of objects and codes for classes | DIN EN IEC 81346-2:2020-10 | replaces DIN EN 81346-2:2010-05 |
| EN 61346 / IEC 61346 | Structuring principles and reference designations | withdrawn | now: DIN EN IEC 81346-1:2024-07 and DIN EN IEC 81346-2:2020-10 |
| DIN 6779-13 | Identification system – chemical plants | DIN 6779-13:2018-01 | replaces DIN 6779-13:2003-06 |
| VGB-S-811-01 (KKS) | KKS Power Plant Classification System – guideline and key part | VGB-S-811-01-2018-01-DE (8th revised edition 2018) | replaces VGB-B 105 |
| DIN 276 | Costs in building construction | DIN 276:2018-12 | replaces DIN 276-1:2008-12; DIN 276-4:2009-08; DIN 277-3:2005-04 |
| DIN EN ISO 10628-1 | Diagrams for the chemical and petrochemical industry – Part 1: Specification of diagrams | DIN EN ISO 10628-1:2015-04 | replaces DIN EN ISO 10628:2001-03 |
| DIN EN ISO 10628-2 | Diagrams for the chemical and petrochemical industry – Part 2: Graphical symbols | DIN EN ISO 10628-2:2013-04 | replaces DIN EN ISO 10628:2001-03 |
| DIN EN ISO 7200 | Technical product documentation – Data fields in title blocks and document headers | DIN EN ISO 7200:2004-05 | replaces DIN 6771-1:1970-12 |
Researched at DIN Media, ISO, IEC and ASME, as of September 2026. Before binding use, please check the current edition with the standards publisher. Overview of all standards: Plant Engineering Infobase · Standards status.