Basic Formal Ontology (BFO) 2020¶
Local reference identifier:
xwkont:ref:bfo-2020Slug:bfo-2020Editorial status:candidateCreated:2026-07-01Modified:2026-07-01
Descriptive Metadata¶
| Field | Value | Notes |
|---|---|---|
| Title | Basic Formal Ontology (BFO) 2020 | Also standardized as ISO/IEC 21838-2:2021. |
| Creator | Barry Smith (lead); BFO Technical Committee | Multiple contributors; do not treat as a complete author list. |
| Contributor | unknown | Full ISO 21838-2 contributor list not verified in this pass. |
| Publisher | International Organization for Standardization (ISO) / International Electrotechnical Commission (IEC); artifacts also hosted at basic-formal-ontology.org | Two distinct publication channels — see Source Relation Notes. |
| Source type | ontology specification / international standard | |
| Version or edition | BFO 2020; ISO/IEC 21838-2:2021 | |
| Identifier or URL | https://www.iso.org/standard/74572.html; https://github.com/BFO-ontology/BFO-2020 | No DOI; ISO standards and GitHub repositories are not DOI-bearing. |
| Access date | 2026-07-01 | |
| Snapshot / Stable identifier | https://basic-formal-ontology.org/BFO-2020/ → http://web.archive.org/web/20240710202903/https://basic-formal-ontology.org/bfo-2020 (2024-07-10); https://github.com/BFO-ontology/BFO-2020 → http://web.archive.org/web/20260607064906/https://github.com/BFO-ontology/BFO-2020 (2026-06-07) |
Both verified retrievable via the Internet Archive Wayback Machine at time of writing, per ADR-0012. |
| Rights/license | unknown (mixed) | The BFO-2020 GitHub repository states its OWL artifacts are available under a Creative Commons license per repository documentation, but this was not independently verified against the repository's LICENSE file in this pass. ISO/IEC 21838-2 itself is a purchasable ISO standard text with its own separate rights terms. Do not conflate the two. |
Source Relation Notes¶
The GitHub repository BFO-ontology/BFO-2020 publishes the same content standardized as ISO/IEC 21838-2:2021. The ISO standard text and the GitHub artifacts are related but distinct publications (different rights terms, potentially different formatting); cite the specific one actually consulted for a given claim.
Rights and License Notes¶
Not fully verified in this pass — see Descriptive Metadata. Do not assert a specific SPDX license for either publication channel until the repository's LICENSE file or the ISO standard's rights terms are directly checked.
Citation and Locator Notes¶
Recommended citation for the standard: ISO/IEC 21838-2:2021, Information technology — Top-level ontologies (TLO) — Part 2: Basic Formal Ontology (BFO). For the open artifacts: BFO-ontology/BFO-2020 GitHub repository, http://basic-formal-ontology.org/BFO-2020/. Cite the Continuant/Occurrent definitions used in docs/crosswalks/concepts/continuant-occurrent.md to the BFO 2020 specification's top-level class definitions.
Direct primary-source verification (2026-07-01): the actual OWL/TTL source (21838-2/owl/bfo-core.ttl in the BFO-ontology/BFO-2020 GitHub repository, master branch) was fetched and read directly to verify exact definitions for continuant-occurrent.md, object.md, event.md, process.md, quality.md, role.md, and relation.md. This corrected one crosswalk claim (event.md: BFO_0000015 "process" carries skos:altLabel "event"@en, contradicting the earlier claim that BFO has no "Event" term at all) and confirmed several others with exact quotations, replacing secondary-source paraphrases. See each crosswalk's own Source Definitions table for the specific quotations and BFO class IRIs (e.g., BFO_0000015 process, BFO_0000019 quality, BFO_0000023 role, BFO_0000030 object, BFO_0000035 process boundary, BFO_0000145 relational quality).
Reused for time.md (2026-07-04): the same bfo-core.ttl was fetched again and read directly to verify the full temporal-region hierarchy: BFO_0000008 (temporal region, "an occurrent over which processes can unfold"), splitting into BFO_0000038 (one-dimensional temporal region) and BFO_0000148 (zero-dimensional temporal region, mutually owl:disjointWith), each specialized further by BFO_0000202 (temporal interval, "continuous, thus without gaps or breaks") and BFO_0000203 (temporal instant, "has no proper temporal part") respectively. temporal region is explicitly enumerated as a subclass of occurrent (BFO_0000003) in the same elucidation that defines occurrent itself. No standalone philosophical-grounding essay for Time found in this file (BFO's elucidations are terse, non-argued glosses throughout, consistent with the rest of this record). See time.md's Source Definitions and correspondence row 001.
Reused for list-sequence.md (2026-07-07): the same 21838-2/owl/bfo-core.ttl was re-fetched and directly grepped for "list," "sequence," "tuple," and "ordered." Found only one informal use of "sequence," inside an Information Content Entity skos:example ("the sequence of this protein molecule"), not a dedicated ordered-collection class. Recorded as a scoped absence. See list-sequence.md's Source Definitions.
Reused for continuous-discrete.md (2026-07-07): the same 21838-2/owl/bfo-core.ttl was re-fetched and grepped for "continuous," "discrete," "gunky," and "granular." Found exactly two hits, both incidental wording inside unrelated elucidations: fiat line ("a one-dimensional continuant fiat boundary that is continuous") and temporal interval ("continuous, thus without gaps or breaks"). No dedicated continuous/discrete class or axis exists in this file. Confirms the crosswalk's draft finding exactly. See continuous-discrete.md's Source Definitions.
Reused for modality.md (2026-07-07): the same 21838-2/owl/bfo-core.ttl was re-fetched and grepped directly for "modal," "modality," "necessity," "possibility," "necessary," "possible," "deontic," and "alethic." Zero hits for any of the eight terms. Confirms the crosswalk's finding of a clean absence exactly. See modality.md's Source Definitions.
Reused for non-physical-social-object.md (2026-07-07, session-048): the same 21838-2/owl/bfo-core.ttl was re-fetched (note: master-branch src/owl/bfo-core.ttl 404s; the correct path is 21838-2/owl/bfo-core.ttl at the repository root, as recorded in every prior reuse note above) and used to confirm generically dependent continuant (BFO_0000031) and immaterial entity. This corrected a citation-fidelity defect in the Codex draft: its correspondence table cited BFO_0000142 for "immaterial entity," but that IRI is actually bfo-core.ttl's "fiat line" class. The correct IRI for "immaterial entity" is BFO_0000141 ("b is an immaterial entity =Def b is an independent continuant which is such that there is no time t when it has a material entity as continuant part"). See non-physical-social-object.md's Source Definitions and correspondence row 002.
Reused for symbol-sign-representation.md (2026-07-07, session-049): the same 21838-2/owl/bfo-core.ttl was re-fetched and grepped directly for "symbol," "sign," "signifier," "representation," "name," and "word." All hits were incidental uses inside unrelated skos:scopeNote/skos:definition text (e.g. "more sophisticated representations of time"), not a dedicated sign/symbol/representation class. Confirms the crosswalk's draft finding of a clean absence exactly. See symbol-sign-representation.md's Source Definitions.