Ontology

UO

Units of measurement ontology

An ontology of units of measurement, used across OBO Foundry ontologies to annotate quantitative values with standard units.

dataplantearth sciencesesslife sciencelife sciences, biologymathematicsmeasurementnfdi4chem
A85

FAIR 45/48

Version 2026-10-12

Evaluated 26 Oct 2026

How scores work

Source & access

Homepagegithub.com DownloadCanonical file / PURL Browse in OLSEMBL-EBI Ontology Lookup ServiceBrowse in BioPortalNCBO BioPortalBrowse in OBO FoundryOBO Foundry registry

Portals & registries

SourceIDVersionClassesPropertiesIndividualsLoaded
OLS (EMBL-EBI)uo2026-10-125741127525 Oct 2026
TIB Terminology Serviceuo2023-05-25572727521 Aug 2023
OBO Dashboarduo2026-07-31574——16 Sept 2026

Ontology IRI http://purl.obolibrary.org/obo/uo.owl
Version IRI http://purl.obolibrary.org/obo/uo/releases/2026-10-12/uo.owl

Languages en

Imports from (1)
IAO

Reused by (48)
AGRO APOLLO_SV DIDEO DRON GENEPIO GEOGEO IAO MCRO MS OBI ONS PDRO RBO SCDO BAO BCGO CAO CHEMINF CHMO CIDO DUO ECO EFO ENM EUPATH FOODON FOVT GENO HCAO HTN ICO MSIO OBCS OBIB OHMI OHPI OMIABIS ONE OOSTT OPMI PBPKO PREFER PRIDE PSDO SLSO STATO SWO VALUESETS

Logical consistency
consistent · 0 unsatisfiable
OWL 2 DL
yes
ROBOT report
0 errors · 320 warnings · 2 info
OBO principles
FP01FP02FP03FP04FP05FP06FP07FP08FP09FP11FP12FP16FP20
Axioms
3,298 · 1.74% entities reused

Also registered as
aberowl: UO agroportal: UO bioportal: UO fairsharing: FAIRsharing.mjnypw obofoundry: uo ols: uo ontobee: UO tib.ts: uo wikidata.entity: Q81661826

Automated evaluation

F Findable FAIR12/12
  • Persistent identifier (F1)purl.obolibrary.org+4
  • Indexed in services (F4)6: OLS, TIB, BioPortal, OBO Foundry, Bioregistry, FAIRsharing+5
  • Citable reference (F2)doi:10.1093/database/bas033+3
A Accessible FAIR12/12
  • Homepage reachableHTTP 200+3
  • Artefact retrievable over HTTP(S) (A1)download HTTP 200+6
  • Metadata persists in a registry (A2)OBO Foundry, Bioregistry+3
I Interoperable FAIR10/12
  • Formal machine-readable format (I1)OWL, OBO+5
  • Semantic-web IRIs (I2)OWL, OBO+3
  • References other vocabularies (I3)imports 1: iao+2
R Reusable FAIR11/12
  • Clear license (R1.1)CC BY 3.0+5
  • Release provenance (R1.2)2026-10-12 (version IRI in the artefact)+4
  • Community standards (R1.3)OBO principles: 10/13 checks pass+2
Q Ontology consistency & quality15/20
  • Logical consistencyconsistent, 0 unsatisfiable classes (OBO Dashboard)+10
  • OWL 2 DL profilein OWL 2 DL+2
  • Upper-ontology alignmentno BFO/COB/DOLCE import found0
  • Standard relations (RO)does not import the Relation Ontology0
  • ROBOT report: no errors0 errors+2
  • ROBOT report: warning density320 warnings / 574 classes = 0.560
  • Pitfall scan: no critical pitfallsno pitfall scan yet; ROBOT report has 0 errors+1
M Maintenance15/16
  • Recency2026-10-14 → 0.4 months (≤ 3 months)+10
  • Release cadence (12 months)4 releases (GitHub releases)+5
U Community adoption10/16
  • Documented adopting projects4 projects+4
  • Reused by other ontologies48: agro, apollo_sv, dideo, dron, genepio, geo…+4
  • Community signalmax(stars 26 → 2, citations 100 → 2)+2
P Penalties (inactivity & inconsistency)0
  • Time since last activity0.0 years → 4 × max(0, 0.0 − 1)0
  • Inactive statusnot archived, legacy or inactive0
  • Consistencyconsistent, no unsatisfiable classes0

FAIR subtotal 45/48 · earned 85/100 = 85/100 → grade A

Community adoption 4

  • (multiple)

    UO has been used in various OBO ontologies, including the Ontology for Biomedical Investigations (OBI), The Statistical Methods Ontology (STATO), and HUGO-PSI Mass spectrometry ontology (MS).

    Source: OBO Foundry registry
  • obi-ontology.org

    The Ontology for Biomedical Investigations (OBI) uses UO terms to specify the units of measurement values recorded in investigations.

    Source: OBO Foundry registry
  • psidev.info

    The HUPO-PSI mass spectrometry controlled vocabulary (PSI-MS) uses UO terms as the units of the quantitative terms it defines for the mzML and related PSI data standards.

    Source: OBO Foundry registry
  • stato-ontology.org

    STATO, the statistical methods ontology, uses UO terms to type the units of the statistical measures and parameters it defines.

    Source: OBO Foundry registry

Know a project that uses UO? Suggest it.

History & changes 1 run

History starts with the first archived run; changes appear after the next evaluation.

RunScoreFAIRVersion evaluatedTermsSnapshot
26 Oct 2026, 03:31 UTC85 A452026-10-12574JSON

Provenance

Every fact on this page was fetched automatically. Each row shows where it came from and when. If a source fails, the last good value is kept and marked “carried forward”.

FactSourceRetrieved
Homepage link check (HTTP 200)github.com26 Oct 2026, 03:27 UTC
Repository link check (HTTP 200)github.com26 Oct 2026, 03:27 UTC
Download link check (HTTP 200)purl.obolibrary.org26 Oct 2026, 03:27 UTC
Artefact header (version IRI)raw.githubusercontent.com26 Oct 2026, 03:27 UTC
Git refs (commit 4e95394, latest tag v2026-10-12)github.com26 Oct 2026, 03:27 UTC
GitHub repository statisticsapi.github.com26 Oct 2026, 03:27 UTC
OLS classes, imports, version & releaseebi.ac.uk26 Oct 2026, 03:27 UTC
OBO Foundry status, license & usagesobofoundry.org26 Oct 2026, 02:37 UTC
TIB Terminology Service metricsservice.tib.eu26 Oct 2026, 03:27 UTC
Bioregistry mappings, dependencies & reusebioregistry.io26 Oct 2026, 03:27 UTC
OBO Dashboard (checked 16 Sept 2026)dashboard.obofoundry.org26 Oct 2026, 02:37 UTC
Crossref citations (doi:10.1093/database/bas033)api.crossref.org26 Oct 2026, 03:27 UTC

Run 2026-10-26T02-37-38Z · evaluator v2.0.0 · rubric v3.4 · entry.json · run snapshot

How to cite