materials
The materials tab of the MatWerk workbook currently holds 25 rows. Every row follows the same shape, and that shape is the pattern below: a entity instance carrying the row's identity, denoted by value node nodes that hold its values, and object properties pointing at entities in other tabs.
Generated from the live sheet and MWO 3.0.1 by scripts/gen_patterns.py — regenerate it rather than editing it by hand.
The pattern
Drag the nodes, change the layout, or use Group to collapse a namespace. The picture is the example only; the declarations and annotations behind it are in
module.ttl.
Columns
| Column | ROBOT | Property | Meaning |
|---|---|---|---|
| Label | A |
rdfs:label |
label |
| Value | A |
nfdi:NFDI_0001007 |
has value |
How to read it
- The entity is typed
mwo:MWO_0001099(material designation) and carries only its identity, its label, and links. - A column marked
Idoes not contain a value — it contains the label of another instance, which ROBOT resolves at build time. That is why every value node needs a unique label, and why a typo produces a silently missing relation rather than an error. - Columns marked
Aare literals on the entity itself.
Query it
Retrieve instances of this pattern from the MatWerk Knowledge Graph (SPARQL endpoint):
SELECT ?x ?label WHERE { ?x a <http://purls.helmholtz-metadaten.de/mwo/MWO_0001099> ; <http://www.w3.org/2000/01/rdf-schema#label> ?label } LIMIT 10
The rows behind it are curated in the materials tab of the workbook.
Competency questions
The questions this pattern exists to answer. Each is answerable against the published graphs.
- Which materials are described in the knowledge graph?
- Which datasets, publications or instruments concern a given material?
Pattern metadata
The Ontology Design Patterns content-ODP annotation schema, in the community's own field order, so a reader who knows ODP pages can read this one without translation.
| Field | Value |
|---|---|
| Name | materials |
| Submitted by | the NFDI-MatWerk consortium |
| Also Known As | the materials template tab of the NFDI-MatWerk workbook |
| Intent | To represent a material designation in the MatWerk Knowledge Graph: its identity, the value nodes that describe it, and its links to the other entities the NFDI-MatWerk consortium records. |
| Domains | research data management; NFDI consortium structure |
| Competency Questions | Which materials are described in the knowledge graph?; Which datasets, publications or instruments concern a given material? |
| Solution description | An entity individual typed mwo:MWO_0001099 carries identity and label; each descriptive value is a separate value node individual reached by obo:IAO_0000235 (denoted by); links to other patterns are object properties onto those entities. Identity is a minted IRI msekg:<epoch_ms><counter>, so re-running the pipeline is idempotent. |
| Reusable OWL Building Block | module.ttl — the example together with the axioms of every term it uses, extracted from the ontology, so the file stands alone |
| Consequences | Values become reusable and independently addressable, and a value may be shared by many entities. The cost: every I reference resolves by label, so labels must be unique and a typo yields a silently missing relation rather than an error. |
| Scenarios | “Nickel” is a material designation. |
| Known Uses | the MatWerk Knowledge Graph (https://nfdi.fiz-karlsruhe.de/matwerk), published as Virtuoso named graphs |
| Web References | https://nfdi-matwerk.de · https://ise-fizkarlsruhe.github.io/mwo/ |
| Other References | https://doi.org/10.1002/adem.202502331 |
| Examples (OWL files) | pattern.ttl — one real row of the tab, with its value nodes resolved |
| Extracted From | the materials tab of the NFDI-MatWerk curation workbook (25 rows at generation time) |
| Reengineered From | the ROBOT template directives in row 2 of that tab |
| Has Components | — |
| Specialization Of | the entity-and-value-node pattern shared by every tab (overview) |
| Related CPs | — |
Provenance and versioning
| Field | Value |
|---|---|
| Pattern version | 1.0.0 |
| Authors | Harald Sack · Jörg Waitelonis · Ebrahim Norouzi · Hossein Beygi Nasrabadi — the authors of the ontology these patterns are derived from (dcterms:creator of MWO 3.0.1) |
| Derived from ontology | MatWerk Ontology (MWO) 3.0.1 — http://purls.helmholtz-metadaten.de/mwo/mwo.owl/3.0.1 |
| Reused ontologies | BFO 2020 (http://purl.obolibrary.org/obo/bfo.owl), NFDIcore (https://nfdi.fiz-karlsruhe.de/ontology/), IAO (http://purl.obolibrary.org/obo/iao.owl), RO (http://purl.obolibrary.org/obo/ro.owl) |
| Ontology licence | CC BY 4.0 (repository); CC0 1.0 declared in the ontology header |
| Cite the ontology as | Hossein Beygi Nasrabadi, Jörg Waitelonis, Ebrahim Norouzi, Kostiantyn Hubaiev, Harald Sack. NFDI MatWerk Ontology (mwo). Revision: v3.0.1. Retrieved from: http://purls.helmholtz-metadaten.de/mwo/3.0.1 |
| Generated | scripts/gen_patterns.py, 2026-08-04 |
Formal characterisation
| Measure | Value |
|---|---|
| Consistency | consistent — ROBOT 1.9.10, reasoner HermiT, merged with MWO 3.0.1 |
| DL expressivity | RRESTRCUCINTUNIVRESTREROIF — measured on the pattern together with a STAR module of exactly the terms it uses, so the figure describes this pattern rather than the whole ontology |
| Axioms / logical axioms | 3 / 1 |
| Classes / individuals | 1 / 1 |
Consistency
pattern.ttl is checked against MWO 3.0.1 with ROBOT (--reasoner hermit) — the same reasoner process_spreadsheets runs over every generated module. A pattern that contradicts the ontology fails the documentation build.