Wiki · iiRDS core concepts · Metadata and classification
iiRDS ExternalClassification: mapping content to ECLASS, VDI 2770 and other systems
Documentation rarely lives alone. Engineering classifies products in ECLASS, document management follows VDI 2770 or IEC 61355, and each system has its own codes. iiRDS, the intelligent information Request and Delivery Standard, carries these codes inside a package with iirds:ExternalClassification, a class of administrative metadata. An external classification consists of a classification identifier, exactly one classification domain and an optional version. Strict rules apply: it is only for classification systems that do not provide IRIs, and it must never replace a proprietary iiRDS extension. This guide explains the structure, the rules, how external classifications differ from information types and identities, and how they connect documentation with product data and AI retrieval.
Valid for iiRDS 1.3Last reviewed Level: Advanced
- Technical documentation
- Machinery
- MedTech
- AI retrieval
Definition
In iiRDS (intelligent information Request and Delivery Standard), an ExternalClassification is administrative metadata that records the class of an iiRDS resource in an external classification system without IRIs, such as ECLASS, VDI 2770 or IEC 61355, as a non-empty iirds:classificationIdentifier, exactly one iirds:ClassificationDomain and an optional iirds:classificationVersion.
An external classification is attached with iirds:has-external-classification, a subproperty of iirds:relates-to-administrative-metadata. According to the specification it may be used on product variants, product features, components, information objects and information units. The code itself goes into iirds:classificationIdentifier; the version or date of the classification system may go into iirds:classificationVersion.
Each classification points to exactly one iirds:ClassificationDomain, which must have an absolute IRI and may state its type with iirds:has-classification-type. The schema provides the types iirds:EclassIRDI, iirds:EclassCodedName and iirds:CDD.
The class belongs to administrative metadata, next to identities. An identity says which item something is in another system; an external classification says which class it belongs to there.
In one sentence
An iiRDS ExternalClassification stores the code a product, component or piece of content has in someone else's classification system, together with the system it belongs to.
Example
A supplier of inductive proximity switches delivers documentation to a machine builder. The component "Proximity switch IPS-12" carries its ECLASS classification as an external classification: the IRDI of the ECLASS class as identifier, the ECLASS release as version, and a classification domain typed iirds:EclassIRDI. The operating manual carries the VDI 2770 class "03-02 Operation". The machine builder's portal already stores ECLASS codes from purchasing, so it attaches the supplier documentation to the right parts automatically, and its document management files the manual under the matching VDI 2770 group.
How it applies
Technical documentation
External classifications let a package speak the language of neighboring systems without changing the iiRDS vocabulary. Take codes from the system of record, whether a PIM, ERP or DMS, rather than typing them into the CMS. Always record the version, because classification systems change their structure between releases.
Migration
PDF documentation often carries VDI 2770 or IEC 61355 classes only in file names or cover sheets; these can be extracted and turned into external classifications on the document. Custom classifications from a legacy CMS that have no external owner belong in a proprietary extension, not here.
MedTech
Device manufacturers work with product catalogs, nomenclatures and internal document classes. Where such a system has no IRIs, an external classification records the code with its domain and version. The code documents a classification; it is not evidence that the device or its documentation conforms to anything.
AI and retrieval
Shared codes make documentation from different suppliers comparable. A retrieval system can group all content classified under the same ECLASS class, or join documentation with product data from a digital product passport or parts list, without first harmonizing each manufacturer's labels.
External classification vs. information type vs. identity
| External classification | Information type | Identity | |
|---|---|---|---|
| Question | Which class in another system? | Which kind of content in iiRDS terms? | Which item in another system? |
| Vocabulary | External, without IRIs | iiRDS standard (plus proprietary) | External numbering scheme |
| Structure | Identifier, one classification domain, optional version | IRI of a type instance | Identifier, one identity domain |
| Example | ECLASS class of a switch | iirds:OperatingInstructions |
Part number 871321 |
In RDF
A component with an ECLASS classification, following the pattern of the specification example. Shown in Turtle for readability; inside a package, metadata.rdf is written in RDF/XML.
@prefix iirds: <http://iirds.tekom.de/iirds#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
<https://example.com/iirds/components/ips-12> a iirds:Component ;
rdfs:label "Proximity switch IPS-12"@en ;
iirds:has-external-classification [
a iirds:ExternalClassification ;
rdfs:label "27-27-40-01 Inductive proximity switch"@en ;
iirds:classificationIdentifier "0173-1---ADVANCED_1_1#01-ADN934#012" ;
iirds:classificationVersion "13.0" ;
iirds:has-classification-domain <https://example.com/classification-domains/eclass-advanced-irdi>
] .
<https://example.com/classification-domains/eclass-advanced-irdi> a iirds:ClassificationDomain ;
rdfs:label "ECLASS Advanced IRDI"@en ;
iirds:has-classification-type iirds:EclassIRDI .
In topic-based authoring and modular architectures
In topic-based authoring, external classifications usually sit on products, components and documents rather than on individual topics, because most external systems classify parts and deliverables. Where a class applies to every version and language of a unit, attach it to the information object once. In a modular delivery architecture, classification domains work like shared reference data: declare each domain once with its IRI and type, and let every generator reference it. That keeps codes from different sources joinable when packages from several suppliers are merged into one machine documentation.
Concept cluster
How this concept connects to the other iiRDS core concepts.
- iiRDS metadataExternal classification is one of the four kinds of administrative metadata in iiRDS.
- iiRDS InformationTypeInformation types use the iiRDS vocabulary; external classifications record classes from other systems, and a document often has both.
- iiRDS InformationObjectInformation objects may carry external classifications that apply to all their versions and languages.
- iiRDS DocumentDocuments are the typical carriers of VDI 2770 or IEC 61355 document classes.
- iiRDS GeneratorGenerators take classification codes from the CMS or PIM and write them into metadata.rdf.
- iiRDS ConsumerConsumers use shared codes to match documentation with product data from other sources.
Also searched as
- iiRDS external classification
- iirds:ExternalClassification
- iiRDS ECLASS
- iiRDS VDI 2770
- classificationIdentifier
- has-external-classification
- ClassificationDomain
- external classification
Questions this article answers:
- how to add ECLASS codes to iiRDS
- iiRDS VDI 2770 document classification
- what is a classification domain in iiRDS
- iiRDS external classification vs proprietary extension
- map IEC 61355 document kinds to iiRDS
Explore further
In the glossary
Frequently asked questions
- What is an external classification in iiRDS?
- It is administrative metadata, iirds:ExternalClassification, that records the class a resource has in an external system such as ECLASS or VDI 2770. It consists of an identifier, a classification domain and an optional version.
- Can I use iiRDS external classification for ECLASS?
- Yes. The specification uses ECLASS as its main example, and the schema provides the classification types iirds:EclassIRDI and iirds:EclassCodedName for the classification domain.
- When must I not use an external classification?
- When the classification is already available as an RDF representation in iiRDS, and never as a substitute for a proprietary iiRDS extension. Vocabularies with their own IRIs are referenced directly.
- What is a classification domain in iiRDS?
- An iirds:ClassificationDomain identifies the classification system within which the identifier is unambiguous. It must have an absolute IRI and may state its type with iirds:has-classification-type.
- Which resources can have an external classification?
- Product variants, product features, components, information objects and information units, linked with iirds:has-external-classification.
- Does an ECLASS or VDI 2770 code make my documentation compliant?
- No. The code records how a resource is classified in another system. Whether documentation meets a standard or regulation depends on its content and process, not on the classification.
Conclusion
iiRDS ExternalClassification is the bridge to the classification systems that engineering, purchasing and document management already use. Keep it for systems without IRIs, give every code a classification domain and a version, and model your own vocabulary as a proprietary extension instead. The result is documentation that can be matched with product data across company boundaries.