Get an area

Where precompiled postcode placements cover this boundary release, the area also includes live and terminated unit-postcode counts from the ONS Postcode Directory edition shown in postcodes.edition.

include expands the area with any of four reports, each under its own key:

capabilities reports geometry, published relationship and crosswalk edges, direct-code named-location membership, and every measure's capability for this exact area, each in the capability vocabulary described by CapabilityStatus: available, partial, requires-conversion, unsupported or not-built, with a reason on every status but available. A measure is available when a source partition published on this release has a value for the area in every period, and partial when it has one in only some periods or its codes only partly join the release. It requires-conversion when no partition is published on the release but a published crosswalk converts one onto it: each entry in conversions names the crosswalk, the source partition and period, and a ready href to the convert route. A conversion is only offered after that exact conversion has been run on the source's latest period and accepted, and only if it reaches this area. A measure whose values do not add over areas is never offered a conversion. capabilities.data.measures lists the available, partial and convertible measures; capabilities.data.counts counts every measure by status, the unsupported ones included. Compatibility is based on area-code membership only and does not assert equal geometry.

citation returns what a caller needs to cite the area as served by this Atlas release: the immutable Atlas release, the content hash of the area identity artifact, the boundary release's publisher, licence and metadata hash, geometry provenance, the validation results for the release and any cited crosswalk, and an attribution block. Name a measure to cite the observation artifacts, with their content hashes, that hold a value for this area in a source partition assessed against this exact boundary release. Only those partitions' datasets are attributed, together with any dataset a derived measure is calculated from. Name a crosswalk to cite one that publishes a relationship for this area. A resource that supplies nothing for the area is refused with 422 rather than cited. Per-area geometry hashes are not compiled yet and are reported as not-published; the boundary release's metadataHash pins its metadata, which names the source file but does not hash its contents. The envelope's top-level atlasRelease is the release of the API response itself: use citation.identity.contentHash for the compiled area identity, citation.boundary.metadataHash for the boundary metadata, and the hashes under citation.measures, citation.crosswalks and citation.geometry for the other artifacts that support a cited result.

metrics measures the area's geometry without transferring its coordinates: its bounding box, centroid, label point, area and perimeter. The same source, reprojection and declared grid corrections apply as for the geometry itself, and metrics.geometrySource records them. Area is ellipsoidal, taken through EPSG:6933 (WGS 84 / NSIDC EASE-Grid 2.0 Global), a Lambert cylindrical equal-area projection on the WGS 84 ellipsoid, so projected area is area on the ellipsoid and no correction is applied; holes are subtracted. Perimeter sums every ring, holes included, each edge's ground length coming from the ellipsoid's radii of curvature at its mid-latitude. The centroid is the centre of area in that same projection, inverted back to WGS 84. labelPoint is guaranteed to lie inside the geometry: the centroid where that falls within the area, otherwise the midpoint of the widest run of interior found on latitudes sampled across the bounding box; labelPointMethod says which was used. These figures describe the boundary as that release publishes it, at its own generalisation. They are not a published land-area statistic: a coastline-clipped boundary still encloses inland water, so they differ from the ONS Standard Area Measurement that population-density uses as its denominator. The method block repeats this with every response. An area whose geometry carries no polygon to measure, such as a release held only as points, is refused with 422 rather than measured as zero.