{"id":"linked-art/api/schema-concept","relativePath":"linked-art/api/schema-concept.md","title":"Linked Art API Schema: Concept","markdown":"# Linked Art API Schema: Concept\n\n**Last refreshed:** 2026-07-06\n\nSource: [Concept schema docs](https://linked.art/api/1.0/schema_docs/concept/) and [concept.json](https://linked.art/api/1.0/schema/concept.json), part of Linked Art API 1.0, published under [CC BY 4.0](http://creativecommons.org/licenses/by/4.0/). This is a project summary; the upstream schema is authoritative.\n\n## Purpose\n\nThe Concept schema describes `crm:E55_Type`: concepts, subjects, and other categorizations. In Linked Art API terms this covers full concept records, including `Type` and subclasses such as `Language`, `Material`, `Currency`, and `MeasurementUnit`.\n\nRelated upstream references:\n\n- [Concept API endpoint](https://linked.art/api/1.0/endpoint/concept/)\n- [Concept model documentation](https://linked.art/model/concept/)\n\n## Top-Level Constraints\n\n- Schema type: object.\n- CRM class: `crm:E55_Type`.\n- Additional top-level properties are not allowed.\n- `@context`: required.\n- `id`: required URI string for the entity.\n- `type`: required class string. Practical Linked Art classes include `Type`, `Language`, `Material`, `Currency`, and `MeasurementUnit`.\n- `_label`: required developer-facing human-readable label.\n\n## Permitted Top-Level Fields\n\n- `classified_as`: array of `Type` structures that classify this concept beyond its class.\n- `identified_by`: array of `Name` or `Identifier` structures.\n- `referred_to_by`: array of embedded statements or textual references about the concept.\n- `equivalent`: array of compact references to equivalent identities in external vocabularies or systems.\n- `representation`: array of embedded `VisualItem` structures linked to digital objects.\n- `member_of`: array of `Set` references.\n- `subject_of`: array of embedded `LinguisticObject` web pages or digital objects focused on this concept.\n- `attributed_by`: array of `AttributeAssignment` structures relating another entity to this concept.\n- `created_by`: creation activity for the intellectual or conceptual entity.\n- `broader`: array of broader concept references, using `skos:broader`.\n\n## Embedded Structures Highlighted By The Schema\n\n`classified_as` items are concept references:\n\n- `id`: required.\n- `type`: required.\n- `_label`, `identified_by`, `classified_as`, `referred_to_by`, and `equivalent` are allowed.\n\n`identified_by` items can be:\n\n- `Name` structures, with required `type` and `content`, plus optional `_label`, nested `identified_by`, `referred_to_by`, `classified_as`, `language`, and `part`.\n- `Identifier` structures, following the shared identifier pattern.\n\n`referred_to_by` items are embedded `LinguisticObject` statements:\n\n- `type`: required.\n- `content`: required.\n- `_label`, `identified_by`, `classified_as`, `referred_to_by`, `language`, and `format` are allowed.\n\n`equivalent` items are compact references:\n\n- `id`: required.\n- `type`: required.\n- `_label`: optional.\n- `equivalent`: optional nested equivalent references.\n\n`representation` items are embedded `VisualItem` structures:\n\n- `type`: required.\n- `_label`, `identified_by`, `classified_as`, `referred_to_by`, and `digitally_shown_by` are allowed.\n- Nested digital objects can carry `access_point`, `format`, and `conforms_to`.\n\n`subject_of` items are embedded `LinguisticObject` structures:\n\n- `type`: required.\n- `_label`, `identified_by`, `classified_as`, `referred_to_by`, `language`, and `digitally_carried_by` are allowed.\n\n`broader` items reference a `Type` or subclass:\n\n- Broader links model concept hierarchy and should remain explicit `skos:broader` relationships.\n- Subclasses can include `Language`, `Material`, `Currency`, and `MeasurementUnit`.\n\n## Creation Activity Shape\n\n`created_by` describes creation of the concept record or conceptual entity. The expanded schema allows normal activity fields:\n\n- `type`\n- `_label`\n- `identified_by`\n- `classified_as`\n- `referred_to_by`\n- `took_place_at`\n- `timespan`\n- `caused_by`\n- `carried_out_by`\n- `used_specific_object`\n- `influenced_by`\n- `technique`\n- `during`\n- `after`\n- `before`\n- `part_of`\n\n`part_of` can reference an `Event` or `Activity` with required `id` and `type`, plus optional `_label` and `equivalent`.\n\n## Meta Museum Notes\n\nMeta Museum already preserves concept classes, vocabulary alignments, `equivalent` links, `notation`, and `broader` relationships in the Concept endpoint notes and shared concept-reference notes. This expanded schema adds the strict endpoint validation target: concept records are full `crm:E55_Type` objects with required identity/label fields and no unexpected top-level properties.\n\nThe highest-value next code task is to validate representative `Type`, `Material`, `Language`, `Currency`, and `MeasurementUnit` records against `concept.json`, including `broader` hierarchy and embedded statement language/format fields.\n\n## Test Ideas\n\n- Validate representative Concept records against `concept.json`.\n- Assert `@context`, `id`, `type`, and `_label` are present.\n- Assert unknown top-level properties fail schema validation.\n- Preserve `broader` as explicit concept hierarchy, not a flattened label.\n- Preserve `representation` visual evidence and `subject_of` web-page evidence.\n- Preserve `created_by` activity fields including `timespan`, `carried_out_by`, `used_specific_object`, `technique`, and `part_of`.\n","sections":[{"level":2,"heading":"Purpose","anchor":"purpose"},{"level":2,"heading":"Top-Level Constraints","anchor":"top-level-constraints"},{"level":2,"heading":"Permitted Top-Level Fields","anchor":"permitted-top-level-fields"},{"level":2,"heading":"Embedded Structures Highlighted By The Schema","anchor":"embedded-structures-highlighted-by-the-schema"},{"level":2,"heading":"Creation Activity Shape","anchor":"creation-activity-shape"},{"level":2,"heading":"Meta Museum Notes","anchor":"meta-museum-notes"},{"level":2,"heading":"Test Ideas","anchor":"test-ideas"}],"html":"<h1 id=\"linked-art-api-schema-concept\">Linked Art API Schema: Concept</h1>\n<p><strong>Last refreshed:</strong> 2026-07-06</p>\n<p>Source: <a href=\"https://linked.art/api/1.0/schema_docs/concept/\" target=\"_blank\" rel=\"noopener noreferrer\" class=\"doc-link\">Concept schema docs</a> and <a href=\"https://linked.art/api/1.0/schema/concept.json\" target=\"_blank\" rel=\"noopener noreferrer\" class=\"doc-link\">concept.json</a>, part of Linked Art API 1.0, published under <a href=\"http://creativecommons.org/licenses/by/4.0/\" target=\"_blank\" rel=\"noopener noreferrer\" class=\"doc-link\">CC BY 4.0</a>. This is a project summary; the upstream schema is authoritative.</p>\n<h2 id=\"purpose\">Purpose</h2>\n<p>The Concept schema describes `crm:E55_Type`: concepts, subjects, and other categorizations. In Linked Art API terms this covers full concept records, including `Type` and subclasses such as `Language`, `Material`, `Currency`, and `MeasurementUnit`.</p>\n<p>Related upstream references:</p>\n<ul><li><a href=\"https://linked.art/api/1.0/endpoint/concept/\" target=\"_blank\" rel=\"noopener noreferrer\" class=\"doc-link\">Concept API endpoint</a></li><li><a href=\"https://linked.art/model/concept/\" target=\"_blank\" rel=\"noopener noreferrer\" class=\"doc-link\">Concept model documentation</a></li></ul>\n<h2 id=\"top-level-constraints\">Top-Level Constraints</h2>\n<ul><li>Schema type: object.</li><li>CRM class: `crm:E55_Type`.</li><li>Additional top-level properties are not allowed.</li><li>`@context`: required.</li><li>`id`: required URI string for the entity.</li><li>`type`: required class string. Practical Linked Art classes include `Type`, `Language`, `Material`, `Currency`, and `MeasurementUnit`.</li><li>`_label`: required developer-facing human-readable label.</li></ul>\n<h2 id=\"permitted-top-level-fields\">Permitted Top-Level Fields</h2>\n<ul><li>`classified_as`: array of `Type` structures that classify this concept beyond its class.</li><li>`identified_by`: array of `Name` or `Identifier` structures.</li><li>`referred_to_by`: array of embedded statements or textual references about the concept.</li><li>`equivalent`: array of compact references to equivalent identities in external vocabularies or systems.</li><li>`representation`: array of embedded `VisualItem` structures linked to digital objects.</li><li>`member_of`: array of `Set` references.</li><li>`subject_of`: array of embedded `LinguisticObject` web pages or digital objects focused on this concept.</li><li>`attributed_by`: array of `AttributeAssignment` structures relating another entity to this concept.</li><li>`created_by`: creation activity for the intellectual or conceptual entity.</li><li>`broader`: array of broader concept references, using `skos:broader`.</li></ul>\n<h2 id=\"embedded-structures-highlighted-by-the-schema\">Embedded Structures Highlighted By The Schema</h2>\n<p>`classified_as` items are concept references:</p>\n<ul><li>`id`: required.</li><li>`type`: required.</li><li>`_label`, `identified_by`, `classified_as`, `referred_to_by`, and `equivalent` are allowed.</li></ul>\n<p>`identified_by` items can be:</p>\n<ul><li>`Name` structures, with required `type` and `content`, plus optional `_label`, nested `identified_by`, `referred_to_by`, `classified_as`, `language`, and `part`.</li><li>`Identifier` structures, following the shared identifier pattern.</li></ul>\n<p>`referred_to_by` items are embedded `LinguisticObject` statements:</p>\n<ul><li>`type`: required.</li><li>`content`: required.</li><li>`_label`, `identified_by`, `classified_as`, `referred_to_by`, `language`, and `format` are allowed.</li></ul>\n<p>`equivalent` items are compact references:</p>\n<ul><li>`id`: required.</li><li>`type`: required.</li><li>`_label`: optional.</li><li>`equivalent`: optional nested equivalent references.</li></ul>\n<p>`representation` items are embedded `VisualItem` structures:</p>\n<ul><li>`type`: required.</li><li>`_label`, `identified_by`, `classified_as`, `referred_to_by`, and `digitally_shown_by` are allowed.</li><li>Nested digital objects can carry `access_point`, `format`, and `conforms_to`.</li></ul>\n<p>`subject_of` items are embedded `LinguisticObject` structures:</p>\n<ul><li>`type`: required.</li><li>`_label`, `identified_by`, `classified_as`, `referred_to_by`, `language`, and `digitally_carried_by` are allowed.</li></ul>\n<p>`broader` items reference a `Type` or subclass:</p>\n<ul><li>Broader links model concept hierarchy and should remain explicit `skos:broader` relationships.</li><li>Subclasses can include `Language`, `Material`, `Currency`, and `MeasurementUnit`.</li></ul>\n<h2 id=\"creation-activity-shape\">Creation Activity Shape</h2>\n<p>`created_by` describes creation of the concept record or conceptual entity. The expanded schema allows normal activity fields:</p>\n<ul><li>`type`</li><li>`_label`</li><li>`identified_by`</li><li>`classified_as`</li><li>`referred_to_by`</li><li>`took_place_at`</li><li>`timespan`</li><li>`caused_by`</li><li>`carried_out_by`</li><li>`used_specific_object`</li><li>`influenced_by`</li><li>`technique`</li><li>`during`</li><li>`after`</li><li>`before`</li><li>`part_of`</li></ul>\n<p>`part_of` can reference an `Event` or `Activity` with required `id` and `type`, plus optional `_label` and `equivalent`.</p>\n<h2 id=\"meta-museum-notes\">Meta Museum Notes</h2>\n<p>Meta Museum already preserves concept classes, vocabulary alignments, `equivalent` links, `notation`, and `broader` relationships in the Concept endpoint notes and shared concept-reference notes. This expanded schema adds the strict endpoint validation target: concept records are full `crm:E55_Type` objects with required identity/label fields and no unexpected top-level properties.</p>\n<p>The highest-value next code task is to validate representative `Type`, `Material`, `Language`, `Currency`, and `MeasurementUnit` records against `concept.json`, including `broader` hierarchy and embedded statement language/format fields.</p>\n<h2 id=\"test-ideas\">Test Ideas</h2>\n<ul><li>Validate representative Concept records against `concept.json`.</li><li>Assert `@context`, `id`, `type`, and `_label` are present.</li><li>Assert unknown top-level properties fail schema validation.</li><li>Preserve `broader` as explicit concept hierarchy, not a flattened label.</li><li>Preserve `representation` visual evidence and `subject_of` web-page evidence.</li><li>Preserve `created_by` activity fields including `timespan`, `carried_out_by`, `used_specific_object`, `technique`, and `part_of`.</li></ul>","updatedAt":"2026-07-06T00:00:00.000Z","checksum":"6a568b387d80f87754e092180b66f22e11b4f6d4ba60a6c6f7163b90462e3c47","checksumPrefix":"6a568b387d80","anchorCount":7,"lineCount":118,"rawUrl":"/api/docs/content?path=linked-art%2Fapi%2Fschema-concept.md","htmlUrl":"/docs?doc=linked-art%2Fapi%2Fschema-concept.md","apiUrl":"/api/docs/content?path=linked-art%2Fapi%2Fschema-concept.md"}