# Beginner Glossary This glossary gives short meanings in the context of OKF Explorer. Follow the linked chapters for the important qualifications. For the curriculum's stable, detailed definitions, use: - [assertion](23-foundational-definitions.md#assertion), [authority](23-foundational-definitions.md#authority) and [channel](23-foundational-definitions.md#channel); - [class](23-foundational-definitions.md#class), [confidence](23-foundational-definitions.md#confidence), [controlled vocabulary](23-foundational-definitions.md#controlled-vocabulary) and [data](23-foundational-definitions.md#data); - [DIKW](23-foundational-definitions.md#dikw), [evidence](23-foundational-definitions.md#evidence), [identifier](23-foundational-definitions.md#identifier), [information](23-foundational-definitions.md#information), [instance](23-foundational-definitions.md#instance) and [IRI](23-foundational-definitions.md#iri); - [jurisdiction](23-foundational-definitions.md#jurisdiction), [knowledge](23-foundational-definitions.md#knowledge), [licence](23-foundational-definitions.md#licence), [life event](23-foundational-definitions.md#life-event) and [observation time](23-foundational-definitions.md#observation-time); - [ontology](23-foundational-definitions.md#ontology), [outcome](23-foundational-definitions.md#outcome), [predicate](23-foundational-definitions.md#predicate), [property](23-foundational-definitions.md#property), [provenance](23-foundational-definitions.md#provenance) and [public service](23-foundational-definitions.md#public-service); - [redress](23-foundational-definitions.md#redress), [requirement](23-foundational-definitions.md#requirement), [rights](23-foundational-definitions.md#rights), [rule](23-foundational-definitions.md#rule), [scope](23-foundational-definitions.md#scope) and [service episode](23-foundational-definitions.md#service-episode); and - [status](23-foundational-definitions.md#status), [taxonomy](23-foundational-definitions.md#taxonomy), [triple](23-foundational-definitions.md#triple), [URI](23-foundational-definitions.md#uri), [URL](23-foundational-definitions.md#url) and [user need](23-foundational-definitions.md#user-need). Their supporting specifications and guidance are annotated in the [authoritative-source register](24-authoritative-source-register.md). ## A–C ### Accessibility Design and implementation that allow people with different access needs and assistive technologies to perceive and operate the product. ### Active context The current overview, search reduction or selected neighbourhood shared across Explorer views. ### Adjacency index An index that locates relationships next to a selected graph node without loading the whole edge collection. ### Agent A model combined with instructions, tools, state and an execution loop. ### API An Application Programming Interface: a machine-oriented contract for one software system to use another. ### Artefact A produced file or data object, such as a manifest, search shard or validation report. ### Approval An authorised decision to proceed after reviewing applicable evidence, limitations and residual risk. Approval does not make an unrun check pass. ### Assertion A statement represented in the data, ideally with status and evidence. ### Attestation Evidence from a declared process that a computation or material satisfied a contract. A declaration is not itself a passing verdict. ### Attribution Visible acknowledgement of a source and applicable rights statement. For a map, attribution applies to every visible geometry and basemap layer rather than only to the pack as a whole, including downloadable or offline artefacts. ### Bundle or pack A published OKF collection and its supporting metadata and indexes. ### BFC, BFE, BGC, BSC and BUC Office for National Statistics boundary-detail abbreviations. `BFC` is a full-resolution clipped boundary; `BFE` is a full-resolution extent-of-the-realm boundary; `BGC` is a generalised 20-metre clipped boundary; `BSC` is a super-generalised 200-metre clipped boundary in products that supply it; and `BUC` is an ultra-generalised 500-metre clipped boundary. `BFE` changes coastal extent, while the other codes combine clipping with different generalisation levels. The code does not, by itself, identify the geography or its vintage. See the [boundary-pack proposal](10-geospatial-data.md#use-the-right-detail-for-the-scale). ### Boundary generalisation Controlled simplification of a boundary's geometry for a declared display scale. It can reduce transfer and rendering cost, but the simplified shape is not a substitute for exact geometry in legal or analytical work. See [use the right detail for the scale](10-geospatial-data.md#use-the-right-detail-for-the-scale). ### Boundary variant A declared treatment of a geography's edge, such as a coastline-clipped or extent-of-the-realm boundary. It is separate from the boundary's [vintage](#boundary-vintage) and [level of detail](#level-of-detail-lod). ### Boundary vintage The validity or as-at date that a boundary represents. It remains separate from source publication or version, upstream modification time, retrieval time and pack-build time. See the [boundary-pack manifest and join](10-geospatial-data.md#proposed-boundary-packs-not-yet-implemented). ### Cache Stored data reused to avoid repeating a fetch or calculation. Browser caches can be evicted, so cached does not automatically mean available offline. ### Candidate One proposed set of source, generated and release bytes being tested and reviewed. It is not yet a final release. ### Cardinality In facets, the number of distinct values. In validation, the permitted number of values for a property. ### Chunk A bounded group of records stored as one artefact. ### Class A category of things in a graph vocabulary. ### CLML Crown Legislation Markup Language, the structured XML used by legislation.gov.uk. ### Closed-world validation Checking a particular publication as complete under declared rules. ### Compression Encoding bytes more compactly for storage or transfer. ### Concept scheme A governed collection of concepts and their labels and relationships, often represented with SKOS. ### Conformance Meeting the requirements of a named standard or profile. ### Context, JSON-LD A mapping from short JSON terms to semantic identifiers. ### Content-addressed Stored or referred to by a [digest](#digest) calculated from the exact bytes. If the bytes change, their content address changes too. See [safe caching and failure](10-geospatial-data.md#safe-caching-and-failure). ### Control plane Descriptor and manifest information that tells the application what data artefacts exist and how to access them. ### Corpus The collection of records under study. ### CORS Browser rules and response headers that control whether one web origin may read resources from another. A cross-origin range-loaded pack also needs readable range responses and stable object identity. ### CRS Coordinate Reference System: the frame that gives coordinate numbers spatial meaning. A geometry pack records both its source CRS and each output CRS or tile matrix, together with the exact transformation. ## D–H ### Data plane The substantial record, relationship, resource and search artefacts described by the control plane. ### DCAT An RDF vocabulary for catalogues, datasets, data services and distributions. ### DCAT-AP A European application profile that states community requirements for DCAT metadata. ### Descriptor The small entry-point document for a large OKF corpus. A proposed geometry-pack reference binds the manifest schema, media type, exact byte count and detached digest before the manifest is parsed. ### Deterministic Producing the same ordered result from the same inputs and declared rules. ### Digest The value produced by applying a named hash algorithm to exact bytes. A consumer recalculates it to check that fetched content matches the expected content. A parent descriptor, not the manifest itself, binds a manifest's detached digest. See [hash](#hash) and the [PMTiles range-integrity boundary](10-geospatial-data.md#use-the-right-detail-for-the-scale). ### Domain profile A bounded, validated handoff recording domain research decisions for a later OKF build. ### Distribution In DCAT, an accessible representation of a dataset, such as a file or API. ### DQV Data Quality Vocabulary, used to describe quality metrics and annotations. ### Edge A graph relationship with a source and target. ### Entailment A statement that follows logically from declared semantic statements and rules. ### Entity An identified thing. In PROV, an item that participates in provenance. ### Facet A dimension and its value counts used to explore and filter a result set. ### Federation An overview-first discovery publication describing independent child bundles and the explicit routes by which they can be loaded. ### Fixture Controlled input stored for repeatable tests. ### Focus node The selected graph node around which a bounded context is displayed. ### Frontmatter Structured metadata at the beginning of a Markdown file. ### GeoJSON A JSON format for geographic features and geometries. ### Geometry representation One particular drawing or encoding of a [semantic geography](#semantic-geography), with its own identifier, format, Coordinate Reference System, level of detail, source item and dates, boundary variant, derivation, digest and rights. Replacing a representation does not create a new geography. ### Gate A named release question with declared evidence and a pass criterion. A gate number has meaning only within its named gate catalogue. ### Gate catalogue The versioned list that defines gate identifiers, titles, required evidence, pass criteria and responsible roles. ### Graph Nodes connected by edges. ### GSS code A Government Statistical Service code used to identify a UK statistical geography. A safe geometry join also records the geography type and boundary [vintage](#boundary-vintage) instead of relying on the code or name alone. Where published, the canonical statistical-geography IRI retains its specified `http` form; a builder must not invent a GSS code. ### Hash A fixed-length fingerprint calculated from bytes, used for integrity checks. ### Hard failure A condition the release contract says must block publication. It cannot be turned into a pass by owner acceptance. ### Hydration Loading fuller data for a compact result or selected record. ## I–P ### IDF Inverse document frequency, a search weighting that values uncommon terms more than terms appearing in most documents. ### Index Precomputed data that makes a question such as term lookup or adjacency faster. ### Independent reviewer A reviewer sufficiently separate from the implementation or expectations under review to reduce self-confirmation. The receipt records the actual role and limitations of that independence. ### Inference Deriving additional statements from declared rules. ### Instance A particular member of a class. ### Integrity Assurance that fetched bytes match an expected hash or signed publication. It does not, by itself, prove publisher authenticity or factual truth. ### IRI Internationalized Resource Identifier, used to identify semantic resources and properties. ### JSON A strict text format for objects, arrays and primitive values. ### JSON-LD JSON for Linked Data, using contexts and identifiers to express an RDF graph. ### JSON Schema A language for validating the structure of JSON values. ### Join table An explicit mapping between two identity systems. A boundary-pack join maps one semantic geography to one logical source feature before tiling; repeated fragments of that feature in several tiles are not duplicate joins. ### Knowledge graph Identified entities and meaningfully typed relationships represented as a graph. ### Lazy loading Deferring an artefact fetch until it is needed. ### Level of detail, LOD One of several representations of the same geometry, prepared with different amounts of detail for particular map scales or zoom ranges. Selecting a lower detail for overview display does not change the geography's identity. See [the proposed display policy](10-geospatial-data.md#use-the-right-detail-for-the-scale). Each LOD records its output CRS or tile matrix, zoom range, error or tolerance and units, quantisation and topology method, counts, bounds and topology checks. ### Literal A value such as a string, number or date in an RDF statement. ### Manifest An inventory of publication artefacts and their locations or integrity data. ### Markdown A plain-text authoring format with headings, links and lightweight notation. ### Materialisation Calculating inferred statements in advance and publishing them as derived data. ### Material, release A file or byte artefact whose identity and digest form part of build or acceptance evidence. ### Metadata Structured information describing a record, artefact or publication. ### Monolithic bundle A bundle containing all records and relationships in one file. ### Node A thing represented in a graph. ### Normalisation Mapping source variation into a documented common representation while preserving provenance. ### Ontology A formal model of classes, properties and semantic relationships that may support inference. ### OpenAPI A machine-readable description of HTTP API operations, inputs, responses and security schemes. ### Open-world assumption The rule that a statement missing from a graph is generally unknown, not false. ### Owner, project or release The person or organisation authorised to decide scope, public claims, exceptions, residual-risk acceptance and release promotion. ### OWL Web Ontology Language, used for expressive class and property semantics. ### Posting An entry connecting a search term or filter value to a document position. ### Predicate The identified property or relationship in an RDF triple. ### Presentation How data is arranged and encoded for a user; it does not change semantic meaning. ### Profile A named set of rules and choices that applies general standards to a publication community. ### Progressive loading Loading overview, result and full-detail artefacts in useful stages. ### Projection A task-oriented view derived from a larger graph or corpus. ### Provenance Evidence about the entities, activities and agents that produced something. ### PWA Progressive Web App, a web application with installable or offline-oriented browser capabilities. ## Q–Z ### RDF Resource Description Framework, a graph model built from subject–predicate– object triples. ### RDFS RDF Schema, which defines basic vocabulary structures such as classes, properties, domain, range and hierarchies. ### Record One described item and its fields in an OKF corpus. ### Receipt A durable record connecting a check or review, its evidence and result to exact inputs, tools, candidate bytes and reviewer roles. ### Registry A discoverable list of bundle entry points. ### Release candidate, RC The proposed final release bytes deployed for last-mile public validation. Final promotion should reuse these exact bytes. ### Release root A digest calculated from an ordered inventory of governed release materials, used to identify the exact candidate covered by evidence and approval. ### Relationship A directed connection between records or concepts. ### Residual risk Risk remaining after controls and checks. An authorised owner may accept it without claiming that missing evidence or an absent audit exists. ### Resource Depending on context, an identified semantic thing or an access/download item attached to a catalogue record. ### Retrieval Selecting evidence relevant to a task through search, filters, relationships and context assembly. ### Route A stable application path identifying a record or view state. ### Schema A formal description of allowed data structure. ### SBOM Software Bill of Materials, a machine-readable inventory of components and dependencies included in a software release. ### Semantic web Standards for publishing identified, machine-interpretable linked data. ### Semantic geography An identified place or area about which assertions are made, independent of the particular files, polygons or tiles used to draw it. It can retain a canonical GSS IRI or another declared source identifier. ### Serialisation A file syntax used to write an abstract data model, such as JSON-LD or Turtle for RDF. ### Sidecar A separate supporting file or package referenced by a primary bundle. A sidecar can carry optional, specialised material such as display geometry without making that material part of the bundle's semantic core. See the [boundary-pack proposal](10-geospatial-data.md#proposed-boundary-packs-not-yet-implemented). ### Shard A deterministic partition of an index or corpus selected from a key. ### SHACL Shapes Constraint Language, used to validate RDF graphs. ### SKOS Simple Knowledge Organization System, used for governed concepts, labels and broader/narrower relationships. ### Snapshot A coherent publication state captured at a stated version or time. ### Source of truth The authoritative editable input from which generated artefacts are rebuilt. ### Source family A researched class of sources in a federation, which may or may not yet have an implemented child bundle. ### Static application A browser application served as prebuilt files without a custom application server handling each interaction. ### Svelte The component framework used by the canonical Explorer. ### Taxonomy A classification, commonly organised as a hierarchy. ### Token, search A normalised unit of text used by a search index. ### Token, security A credential representing authority. This is a different meaning from a search token or model token. ### Triple An RDF statement with subject, predicate and object. ### Truncation A declared limit that prevented retrieval or preview from processing every possible result. ### Turtle A compact text serialisation for RDF graphs. ### TypeScript JavaScript with development-time types, used by the canonical Explorer. ### Validation Checking data against declared rules. ### Waiver An authorised, recorded exception to a non-hard requirement. A waiver does not apply to a declared hard failure unless the governing contract itself is changed and re-reviewed. ### Vocabulary A governed set of identified terms and descriptions. ### Web Worker A browser background execution context used to keep large search work off the interface thread. ### YAML A human-oriented structured data notation used in frontmatter and semantic source files. ### YAML-LD YAML-authored linked data that is parsed under constrained rules and projected to JSON-LD in this repository. ## Continue Learning Return to the [learning-path index](index.md) or use the repository's more specialised [AI infrastructure glossary](../../glossary/index.md).