<td><code>geom</code></td>

<td>http://data.ordnancesurvey.co.uk/ontology/geometry/</td>

<td><ahref="https://www.ordnancesurvey.co.uk/">Ordnance Survey's</a><ahref="https://www.ordnancesurvey.co.uk/products/linked-data/">Geometry Ontology</a></td>

<td><ahref="https://www.ordnancesurvey.co.uk/">Ordnance Survey's</a><ahref="https://www.ordnancesurvey.co.uk/products/linked-data">Geometry Ontology</a></td>

<td><code>geonames</code></td>

<p>In addition to the<a>spatial relationships</a> that are applicable to a wide variety of domains, there are a huge number of cases where asserting a relationship between<a>Spatial Thing</a> is useful. Clearly, enumerating all these cases is more than we can do here &mdash; but we can look at some of those that commonly occur.</p>

<p>First, there are the properties used to describe relationships between<a>Spatial Things</a> in a<em>gazetteer</em>. These properties are often used in combination with spatial predicates to describe the relationship between administrative units. For example,<ahref="https://www.ordnancesurvey.co.uk">Ordnance Survey</a> define specific properties to describe the relationships between the administrative units used within the UK:<ahref="https://data.ordnancesurvey.co.uk/ontology/admingeo/county"><code>county</code></a>,<ahref="https://data.ordnancesurvey.co.uk/ontology/admingeo/district"><code>district</code></a>,<ahref="https://data.ordnancesurvey.co.uk/ontology/admingeo/ward"><code>ward</code></a>, etc.</p>

<p>First, there are the properties used to describe relationships between<a>Spatial Things</a> in a<em>gazetteer</em>. These properties are often used in combination with spatial predicates to describe the relationship between administrative units. For example,<ahref="https://www.ordnancesurvey.co.uk">Ordnance Survey</a> define specific properties to describe the relationships between the administrative units used within the UK:<ahref="https://www.ordnancesurvey.co.uk/linked-data/ontology/admingeo/admingeo.ttl"><code>county (admingeo:county)</code></a>,<ahref="https://www.ordnancesurvey.co.uk/linked-data/ontology/admingeo/admingeo.ttl"><code>district (admingeo:district)</code></a>,<ahref="https://www.ordnancesurvey.co.uk/linked-data/ontology/admingeo/admingeo.ttl"><code>ward (admingeo:ward)</code></a>, etc.</p>

<asideclass="example"id="ex-linking-gazetteer-edinburgh"title="Asserting gazetteer relationships for the City of Edinburgh Council Area (TTL format)">

<p>The example snippet above, provided in [[TURTLE]] format, shows the relationships between the<ahref="https://www.ordnancesurvey.co.uk/products/linked-data">City of Edinburgh (osuk:7000000000030505)</a><ahref="https://data.ordnancesurvey.co.uk/ontology/admingeo/District">district</a> and the<ahref="https://data.ordnancesurvey.co.uk/ontology/admingeo/Ward">electoral wards</a> it contains. Also note that complementary use of<ahref="http://www.opengis.net/ont/geosparql#sfTouches"><code>geosparql:sfTouches</code></a> to relate the<ahref="https://www.ordnancesurvey.co.uk/products/linked-data">City of Edinburgh (osuk:7000000000030505)</a> to its adjacent districts; Midlothian, West Lothian etc.</p>

<p>The example snippet above, provided in [[TURTLE]] format, shows the relationships between the<ahref="https://www.ordnancesurvey.co.uk/products/linked-data">City of Edinburgh (osuk:7000000000030505)</a><ahref="https://www.ordnancesurvey.co.uk/linked-data/ontology/admingeo/admingeo.ttl">district (admingeo:district)</a> and the<ahref="https://www.ordnancesurvey.co.uk/linked-data/ontology/admingeo/admingeo.ttl">electoral wards (admingeo:ward)</a> it contains. Also note that complementary use of<ahref="http://www.opengis.net/ont/geosparql#sfTouches"><code>geosparql:sfTouches</code></a> to relate the<ahref="https://www.ordnancesurvey.co.uk/products/linked-data">City of Edinburgh (osuk:7000000000030505)</a> to its adjacent districts; Midlothian, West Lothian etc.</p>

<p>A second domain where relationships between<a>Spatial Things</a> and non-spatial resources occur is earth observing. The example below, provided in [[GML]], relates a monitoring point at Deddington on the Nile River, Tasmania, to the sensor that is deployed there (using the<code>sams:hostedProcedure</code> property) and relates that monitoring point to the waterbody whose properties are being measured (using the<code>sam:sampledFeature</code> property). Here, the<a>links</a> are defined using [[XLINK11]].</p>

<li>Revised<ahref="#ex-geodcat-ap-bag-addresses"></a> in<ahref="#describe-geometry"class="practiceRef"></a>. Property<code>locn:geometry</code> has been replaced with the more specific property<ahref="https://www.w3.org/TR/vocab-dcat-2/#Property:location_bbox"><code>dcat:bbox</code></a>, defined in [[VOCAB-DCAT-2]]. Moreover, the original GeoJSON datatype URI used in the example (corresponding to<ahref="https://www.iana.org/assignments/media-types/application/geo+json">the GeoJSON IANA Media Type URL</a>) has been replaced with<code>geosparql:geoJSONLiteral</code>, included in the draft of the new version of [[GeoSPARQL]] (see issues<ahref="https://github.com/opengeospatial/ogc-geosparql/issues/1">opengeospatial/ogc-geosparql/issues/1</a> and<ahref="https://github.com/opengeospatial/ogc-geosparql/issues/48">opengeospatial/ogc-geosparql/issues/48</a>), and already adopted in [[GeoDCAT-AP-20201223]].</li>

<li>Revised<ahref="#ex-anne-frank-building-centroid-and-bbox"></a> in<ahref="#multiplegeometries"class="practiceRef"></a>, to include an example on the use of [[VOCAB-DCAT-2]] for the specification of centroids (<ahref="https://www.w3.org/TR/vocab-dcat-2/#Property:location_centroid"><code>dcat:centroid</code></a>) and bounding boxes (<ahref="https://www.w3.org/TR/vocab-dcat-2/#Property:location_bbox"><code>dcat:bbox</code></a>).</li>

<li>Revised<ahref="#ex-geodcat-ap-dataset-spatial-representation-type"></a> in<ahref="#spatial-info-dataset-metadata"class="practiceRef"></a>, following the release of the spatial representation type code list of the<ahref="http://inspire.ec.europa.eu/metadata-codelist/SpatialRepresentationType">INSPIRE Registry</a>.</li>

<li>Revised<ahref="#ex-geodcat-ap-dataset-spatial-representation-type"></a> in<ahref="#spatial-info-dataset-metadata"class="practiceRef"></a>, following the release of the spatial representation type code list of the<ahref="https://inspire.ec.europa.eu/metadata-codelist/SpatialRepresentationType">INSPIRE Registry</a>.</li>

<li>Revised<ahref="#ex-dqv-dataset-quality"></a> in<ahref="#desc-accuracy"class="practiceRef"></a>, to use the<ahref="http://qudt.org/vocab/unit/">QUDT Units Vocabulary</a> instead of the<ahref="https://github.com/HajoRijgersberg/OM/blob/master/README.md">Ontology of units of Measure (OM)</a> (used originally), and to include the statements describing<code>:myDatasetAccuracy</code> and<code>:spatialAccuracy</code>, which are available from the reference [[VOCAB-DQV]] examples in<ahref="https://www.w3.org/TR/vocab-dqv/#h-expressdatasetaccuracyprecision">the relevant section</a>.</li>

<li>Added<ahref="#ex-dcat-dataset-quality"></a> and<ahref="#ex-geodcat-ap-spatial-resolution"></a> in<ahref="#desc-accuracy"class="practiceRef"></a>, to illustrate the use of [[VOCAB-DCAT-2]] and [[GeoDCAT-AP-20201223]], respectively, for the specification of spatial precision and accuracy.</li>

<li>Revised second table in<ahref="#applicability-formatVbp"></a> to include a column for [[VOCAB-DCAT-2]].</li>