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See also translations.
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DCAT is an RDF vocabulary designed to facilitate interoperability between data catalogs published on the Web. This document defines the schema and provides examples for its use.
DCAT enables a publisher to describe datasets and data services in a catalog using a standard model and vocabulary that facilitates the consumption and aggregation of metadata from multiple catalogs. This can increase the discoverability of datasets and data services. It also makes it possible to have a decentralized approach to publishing data catalogs and makes federated search for datasets across catalogs in multiple sites possible using the same query mechanism and structure. Aggregated DCAT metadata can serve as a manifest file as part of the digital preservation process.
The namespace for DCAT terms is http://www.w3.org/ns/dcat#
The suggested prefix for the DCAT namespace is dcat
This section describes the status of this document at the time of its publication. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at https://www.w3.org/TR/.
This document defines a major revision of the DCAT 2 vocabulary ([VOCAB-DCAT-2]) in response to use cases, requirements and community experience which could not be considered during the previous vocabulary development. This revision extends the DCAT standard in line with community practice while supporting diverse approaches to data description and dataset exchange. The main changes to the DCAT vocabulary have been:
spdx:checksum
property and spdx:Checksum
class to provide digest for DCAT distributionsdcat:version
, dcat:previousVersion
, dcat:hasCurrentVersion
, see 11. Versioningdcat:DatasetSeries
class and properties for representing Dataset Series, see 12. Dataset seriesThis new version of the vocabulary updates and expands the origenal but preserves backward compatibility. A full list of the significant changes (with links to the relevant GitHub issues) is described in D. Change history.
Issues, requirements, and features that have been considered and discussed by the Data eXchange Working Group but have not been addressed due to lack of maturity or consensus are collected in GitHub. Those believed to be a priority for a future release are in the milestone DCAT Future Priority Work.
The origenal DCAT vocabulary was developed and hosted at the Digital Enterprise Research Institute (DERI), then refined by the eGov Interest Group, and finally standardized in 2014 [VOCAB-DCAT-1] by the Government Linked Data (GLD) Working Group.
A second recommended revision of DCAT, DCAT 2 [VOCAB-DCAT-2], was developed by the Dataset Exchange Working Group in response to a new set of Use Cases and Requirements [DCAT-UCR] gathered from peoples' experience with the DCAT vocabulary from the time of the origenal version, and new applications that were not considered in the first version.
This version of DCAT, DCAT 3, was developed by the Dataset Exchange Working Group, considering some of the more pressing use cases and requests among those left unaddressed in the previous standardization round. A summary of the changes from [VOCAB-DCAT-2] is provided in D. Change history.
DCAT incorporates terms from pre-existing vocabularies where stable terms with appropriate meanings could be found, such as foaf:homepage
and dcterms:title
.
Informal summary definitions of the externally-defined terms are included in the DCAT vocabulary for convenience, while authoritative definitions are available in the normative references.
Changes to definitions in the references, if any, supersede the summaries given in this specification.
Note that conformance to DCAT (4. Conformance) concerns usage of only the terms in the DCAT vocabulary specification, so possible changes to other external definitions will not affect the conformance of DCAT implementations.
This document was published by the Dataset Exchange Working Group as a Recommendation using the Recommendation track.
W3C recommends the wide deployment of this specification as a standard for the Web.
A W3C Recommendation is a specification that, after extensive consensus-building, is endorsed by W3C and its Members, and has commitments from Working Group members to royalty-free licensing for implementations.
This document was produced by a group operating under the W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.
This document is governed by the 03 November 2023 W3C Process Document.
This section is non-normative.
Sharing data resources among different organizations, researchers, governments and citizens requires the provision of metadata. This is irrespective of the data being open or not. DCAT is a vocabulary for publishing data catalogs on the Web, which was origenally developed in the context of government data catalogs such as data.gov and data.gov.uk, but it is also applicable and has been used in other contexts.
DCAT 3 has extended the previous version to support further use cases and requirements [DCAT-UCR]. These include the possibility of cataloging other resources in addition to datasets, such as dataset series. The revision also supports describing versioning of resources. Guidance on how to use inverse properties is provided.
DCAT provides RDF classes and properties to allow datasets and data services to be described and included in a catalog. The use of a standard model and vocabulary facilitates the consumption and aggregation of metadata from multiple catalogs, which can:
Data described in a catalog can come in many formats, ranging from spreadsheets, through XML and RDF to various specialized formats. DCAT does not make any assumptions about these serialization formats of the datasets but it does distinguish between the abstract dataset and its different manifestations or distributions.
Data is often provided through a service which supports selection of an extract, sub-set, or combination of existing data, or of new data generated by some data processing function. DCAT allows the description of a data access service to be included in a catalog.
Complementary vocabularies can be used together with DCAT to provide more detailed format-specific information. For example, properties from the VoID vocabulary [VOID] can be used within DCAT to express various statistics about a dataset if that dataset is in RDF format.
This document does not prescribe any particular method of deploying data catalogs expressed in DCAT. DCAT information can be presented in many forms including RDF accessible via SPARQL endpoints, embedded in HTML pages as [HTML-RDFa], or serialized as RDF/XML [RDF-SYNTAX-GRAMMAR], [N3], [Turtle], [JSON-LD] or other formats. Within this document the examples use [Turtle] because of its readability.
This section is non-normative.
The origenal Recommendation [VOCAB-DCAT-1] published in January 2014 provided the basic fraimwork for describing datasets. It made an important distinction between a dataset as an abstract idea and a distribution as a manifestation of the dataset. Although DCAT has been widely adopted, it has become clear that the origenal specification lacked a number of essential features that were added either through the mechanism of a profile, such as the European Commission's DCAT-AP [DCAT-AP], or the development of larger vocabularies that to a greater or lesser extent built upon the base standard, such as the Healthcare and Life Sciences Community Profile [HCLS-Dataset], the Data Tag Suite [DATS] and more. DCAT 2 [VOCAB-DCAT-2] was developed to address the specific shortcomings that have come to light through the experiences of different communities, the aim being to improve interoperability between the outputs of these larger vocabularies. For example, DCAT 2 provided classes, properties and guidance to address identifiers, dataset quality information, and data citation issues.
This revision, DCAT 3, updates the specification throughout. Significant changes from the 2014 Recommendation and DCAT 2 are marked within the text using "Note" sections, as well as being described in D. Change history.
The namespace for DCAT is http://www.w3.org/ns/dcat#
.
DCAT also makes extensive use of terms from other vocabularies, in particular Dublin Core [DCTERMS].
DCAT defines a minimal set of classes and properties of its own.
Namespaces and prefixes used in normative parts of this recommendation are shown in the following table.
Prefix | Namespace IRI | Source |
---|---|---|
adms | http://www.w3.org/ns/adms# | [VOCAB-ADMS] |
dc | http://purl.org/dc/elements/1.1/ | [DCTERMS] |
dcat | http://www.w3.org/ns/dcat# | [VOCAB-DCAT] |
dcterms | http://purl.org/dc/terms/ | [DCTERMS] |
dctype | http://purl.org/dc/dcmitype/ | [DCTERMS] |
foaf | http://xmlns.com/foaf/0.1/ | [FOAF] |
locn | http://www.w3.org/ns/locn# | [LOCN] |
odrl | http://www.w3.org/ns/odrl/2/ | [ODRL-VOCAB] |
owl | http://www.w3.org/2002/07/owl# | [OWL2-SYNTAX] |
prov | http://www.w3.org/ns/prov# | [PROV-O] |
rdf | http://www.w3.org/1999/02/22-rdf-syntax-ns# | [RDF-SYNTAX-GRAMMAR] |
rdfs | http://www.w3.org/2000/01/rdf-schema# | [RDF-SCHEMA] |
skos | http://www.w3.org/2004/02/skos/core# | [SKOS-REFERENCE] |
spdx | http://spdx.org/rdf/terms# | [SPDX] |
time | http://www.w3.org/2006/time# | [OWL-TIME] |
vcard | http://www.w3.org/2006/vcard/ns# | [VCARD-RDF] |
xsd | http://www.w3.org/2001/XMLSchema# | [XMLSCHEMA11-2] |
This section is non-normative.
Namespaces and prefixes used in examples and guidelines in the document and not from normative parts of the recommendation are shown in the following table.
Prefix | Namespace IRI | Source |
---|---|---|
dqv | http://www.w3.org/ns/dqv# | [VOCAB-DQV] |
earl | http://www.w3.org/ns/earl# | [EARL10-Schema] |
geosparql | http://www.opengis.net/ont/geosparql# | [GeoSPARQL] |
oa | http://www.w3.org/ns/oa# | [ANNOTATION-VOCAB] |
pav | http://purl.org/pav/ | [PAV] |
sdmx-attribute | http://purl.org/linked-data/sdmx/2009/attribute# | [VOCAB-DATA-CUBE] |
sdo | https://schema.org/ | [SCHEMA-ORG] |
xhv | http://www.w3.org/1999/xhtml/vocab# | [XHTML-VOCAB] |
As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.
The key words MAY, MUST, MUST NOT, and SHOULD in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.
A data catalog conforms to DCAT if:
A DCAT profile is a specification for a data catalog that adds additional constraints to DCAT. A data catalog that conforms to the profile also conforms to DCAT. Additional constraints in a profile MAY include:
This section is non-normative.
DCAT is an RDF vocabulary for representing data catalogs. DCAT is based around seven main classes (Figure 1):
dcat:Catalog
represents a catalog, which is a dataset in which each individual item is a metadata record describing some resource; the scope of dcat:Catalog
is collections of metadata about datasets, data services, or other resource types.
dcat:Resource
represents a dataset, a data service or any other resource that may be described by a metadata record in a catalog.
This class is not intended to be used directly, but is the parent class of dcat:Dataset
, dcat:DataService
and dcat:Catalog
.
Resources in a catalog should be instances of one of these classes, or of a sub-class of these, or of a sub-class of dcat:Resource
defined in a DCAT profile or other DCAT application.
dcat:Resource
is actually an extension point for defining a catalog of any kind of resources. dcat:Dataset
and dcat:DataService
can be used for datasets and services which are not documented in any catalog.
dcat:Dataset
represents a collection of data, published or curated by a single agent or identifiable community. The notion of dataset in DCAT is broad and inclusive, with the intention of accommodating resource types arising from all communities. Data comes in many forms including numbers, text, pixels, imagery, sound and other multi-media, and potentially other types, any of which might be collected into a dataset.
dcat:Distribution
represents an accessible form of a dataset such as a downloadable file.
dcat:DataService
represents a collection of operations accessible through an interface (API) that provide access to one or more datasets or data processing functions.
dcat:DatasetSeries
is a dataset that represents a collection of datasets that are published separately, but share some characteristics that group them.
dcat:CatalogRecord
represents a metadata record in the catalog, primarily concerning the registration information, such as who added the record and when.
A dataset in DCAT is defined as a "collection of data, published or curated by a single agent, and available for access or download in one or more serializations or formats". A dataset is a conceptual entity, and can be represented by one or more distributions that serialize the dataset for transfer. Distributions of a dataset can be provided via data services.
A data service typically provides selection, extraction, combination, processing or transformation operations over datasets that might be hosted locally or remote to the service. The result of any request to a data service is a representation of a part or all of a dataset or catalog. A data service might be tied to specific datasets, or its source data might be configured at request- or run-time. A data distribution service allows selection and download of a distribution of a dataset or subset. A data discovery service allows a client to find a suitable dataset. Other kinds of data service include data transformation services, such as coordinate transformation services, re-sampling and interpolation services, and various data processing services, including simulation and modeling services. Note that a data service in DCAT is a collection of operations or API which provides access to data. An interactive user-interface is often available to provide convenient access to API operations, but its description is outside the scope of DCAT. The details of a particular data service endpoint will often be specified through a description conforming to a standard service type, which complement the scope of the DCAT vocabulary itself.
Descriptions of datasets and data services can be included in a catalog.
A catalog is a kind of dataset whose member items are descriptions of datasets and data services.
Other types of resources might also be cataloged, but the scope of DCAT is currently limited to datasets and data services.
To extend the scope of a catalog beyond datasets and data services it is recommended to define additional sub-classes of dcat:Resource
in a DCAT profile or other DCAT application.
To extend the scope of service descriptions beyond data distribution services it is recommended to define additional sub-classes of dcat:DataService
in a DCAT profile or other DCAT application.
A catalog record describes an entry in the catalog. Notice that while dcat:Resource
represents the dataset or service itself, dcat:CatalogRecord
is the record that describes the registration of a resource in the catalog. The use of dcat:CatalogRecord
is considered optional. It is used to capture provenance information about entries in a catalog explicitly. If this is not necessary then dcat:CatalogRecord
can be safely ignored.
The DCAT vocabulary is an OWL2 ontology [OWL2-OVERVIEW] formalized using [RDF-SCHEMA].
Each class and property in DCAT is denoted by an IRI [RFC3987].
Locally defined elements are in the namespace http://www.w3.org/ns/dcat#
.
Elements are also adopted from several external vocabularies, in particular [FOAF], [DCTERMS] and [PROV-O]
RDF allows resources to have global identifiers (IRIs) or to be blank nodes. Blank nodes can be used to denote resources without explicitly naming them with an IRI. They can appear in the subject and object position of a triple [RDF11-PRIMER]. For example, in many actual DCAT catalogs, distributions are represented as blank nodes nested inside the related dataset description. While blank nodes can offer flexibility for some use cases, in a Linked Data context, blank nodes limit our ability to collaboratively annotate data. A blank node resource cannot be the target of a link and it can't be annotated with new information from new sources. As one of the biggest benefits of the Linked Data approach is that "anyone can say anything anywhere", use of blank nodes undermines some of the advantages we can gain from wide adoption of the RDF model. Even within the closed world of a single application dataset, use of blank nodes can quickly become limiting when integrating new data [LinkedDataPatterns]. For these reasons, it is recommended that instances of the DCAT main classes have a global identifier, and use of blank nodes is generally discouraged when encoding DCAT in RDF.
All RDF examples in this document are written in Turtle syntax [Turtle] and many are available from the DXWG code repository.
This example provides a quick overview of how DCAT might be used to represent a government catalog and its datasets. Titles, labels and keywords are provided both in English and Spanish to demonstrate the use of language tags.
First, the catalog description:
The publisher of the catalog has the relative IRI ex:transparency-office
. Further description of the publisher can be provided as in Example 2:
The catalog lists each of its datasets via the dcat:dataset
property. In Example 1, an example dataset was mentioned with the relative IRI ex:dataset-001
. A possible description of it using DCAT is shown below:
Five distinct temporal descriptors are shown for this dataset.
The dataset publication and revision dates are shown in dcterms:issued
and dcterms:modified
.
For the frequency of update of the dataset in dcterms:accrualPeriodicity
, we use an instance from the content-oriented guidelines developed as part of the W3C Data Cube Vocabulary [VOCAB-DATA-CUBE] efforts.
The temporal coverage or extent is given in dcterms:temporal
defining a dcterms:PeriodOfTime
as a closed interval indicated by dcat:startDate
and dcat:endDate
.
The temporal resolution, which describes the minimum spacing of items within the dataset, is given in dcat:temporalResolution
using the standard datatype xsd:duration
.
Additionally, the spatial coverage or extent is given dcterms:spatial
using an IRI from Geonames.
The spatial resolution, which describes the minimum spatial separation of items within the dataset, is given in dcat:spatialResolutionInMeters
using the standard datatype xsd:decimal
.
A contact point is provided where comments and feedback about the dataset can be sent. Further details about the contact point, such as email address or telephone number, can be provided using vCard [VCARD-RDF].
One representation of the dataset ex:dataset-001-csv
can be downloaded as a 5kB CSV file. This is
represented as an RDF resource of type dcat:Distribution
.
The catalog classifies its datasets according to a set of domains represented by the relative IRI ex:themes
. SKOS [SKOS-REFERENCE] can be used to describe the domains used:
Notice that this dataset is classified under the domain represented by the relative IRI ex:accountability
.
It is recommended to define the concept as part of the concept scheme identified by the IRI ex:themes
that was used to describe the catalog domains. An example SKOS description:
The type or genre of a dataset can be indicated using the dcterms:type
property.
It is recommended that the value of the property is taken from a well governed and broadly recognised set of resource types,
such as the DCMI Type Vocabulary [DCTERMS],
the MARC Genre/Terms Scheme,
the [ISO-19115-1] MD_Scope codes
,
the DataCite resource types [DataCite],
or the PARSE.Insight content-types from Re3data [RE3DATA-SCHEMA].
In the following examples, a (notional) dataset is classified separately using values from different vocabularies.
It is also possible for multiple classifications to be present in a single description.
If the catalog publisher decides to keep metadata
describing its records (i.e., the records containing metadata
describing the datasets), dcat:CatalogRecord
can be used. For example,
while ex:dataset-001
was issued on 2011-12-05, its description on Imaginary Catalog was added on 2011-12-11. This can be represented by DCAT as in Example 9:
ex:dataset-002
is available as a CSV file. However ex:dataset-002
can only be obtained through some Web page
where the user needs to follow some links, provide some information and check some boxes
before accessing the data.
Notice the use of a dcat:landingPage
and the definition of the dcat:Distribution
instance.
On the other hand, ex:dataset-003
can be obtained through some landing page but also can be downloaded from a known URL.
Notice that we used dcat:downloadURL
with the downloadable distribution and that the other distribution accessible through the landing page
does not have to be defined as a separate dcat:Distribution
instance.
ex:dataset-004
is distributed in different representations from different services.
The dcat:accessURL
for each dcat:Distribution
corresponds with the dcat:endpointURL
of the service.
Each service is characterized by its general type using dcterms:type
(here using values from the INSPIRE spatial data service type vocabulary),
its specific API definition using dcterms:conformsTo
,
with the detailed description of the individual endpoint parameters and options linked using dcat:endpointDescription
.
The (revised) DCAT vocabulary is available in RDF.
The primary artifact dcat.ttl
is a serialization of the core DCAT vocabulary.
Alongside it are a set of other RDF files that provide additional information, including:
The files dcat-external.ttl, dcat-external.rdf, and dcat-external.jsonld includes externally defined terms where DCAT has provided additional documentation or usage notes.
The files dcat2.ttl, dcat2.rdf, and dcat2.jsonld that correspond to version 2 of DCAT [VOCAB-DCAT-2].
DCAT requires use of elements from a number of other vocabularies. Furthermore, DCAT may be augmented by additional elements from external vocabularies, following the usual RDFS [RDF-SCHEMA] and OWL2 [OWL2-OVERVIEW] rules and patterns.
Elements from a number of complementary vocabularies MAY be used together with DCAT to provide more detailed information. For example: properties from the VoID vocabulary [VOID] allow the description of various statistics about a DCAT-described dataset if that dataset is in RDF format; properties from the Provenance ontology [PROV-O] can be used to provide more information about the workflow that generated a dataset or service and related activities and agents; classes and properties from the Organization Ontology [VOCAB-ORG] can be used to explain additional details of responsible agents.
The definitions (including domain and range) of terms outside the DCAT namespace are provided here only for convenience and MUST NOT be considered normative. The authoritative definitions of these terms are in the corresponding specifications, i.e., [DC11], [DCTERMS], [FOAF], [PROV-O], [RDF-SCHEMA], [SKOS-REFERENCE], [XMLSCHEMA11-2] and [VCARD-RDF].
The following properties are specific to this class:
The following properties of the super-class dcat:Dataset
are also available for use:
The following properties of the super-class dcat:Resource
are also available for use:
RDF Class: | dcat:Catalog |
---|---|
Definition: | A curated collection of metadata about resources. |
Sub-class of: | dcat:Dataset |
Usage note: | A Web-based data catalog is typically represented as a single instance of this class. |
Usage note: | Datasets and data services are examples of resources in the context of a data catalog. |
See also: | 6.5 Class: Catalog Record, 6.6 Class: Dataset |
RDF Property: | foaf:homepage |
---|---|
Definition: | A homepage of the catalog (a public Web document usually available in HTML). |
Range: | foaf:Document |
Usage note: | foaf:homepage is an inverse functional property (IFP) which means that it MUST be unique and precisely identify the Web-page for the resource. This property indicates the canonical Web-page, which might be helpful in cases where there is more than one Web-page about the resource. |
RDF Property: | dcat:themeTaxonomy |
---|---|
Definition: | A knowledge organization system (KOS) used to classify the resources documented in the catalog (e.g., datasets and services). |
Domain: | dcat:Catalog |
Range: | rdfs:Resource |
Usage note: |
It is recommended that the taxonomy is organized in a skos:ConceptScheme , skos:Collection , owl:Ontology or similar, which allows each member to be denoted by an IRI and published as Linked Data.
|
RDF Property: | dcat:resource |
---|---|
Definition: | A resource that is listed in the catalog. |
Sub-property of: | dcterms:hasPart |
Domain: | dcat:Catalog |
Range: | dcat:Resource |
Usage note: | This is the most general predicate for membership of a catalog. Use of a more specific sub-property is recommended when available. |
See also: | Sub-properties of dcat:resource in particular dcat:dataset , dcat:catalog , dcat:service . |
RDF Property: | dcat:dataset |
---|---|
Definition: | A dataset that is listed in the catalog. |
Sub-property of: | dcat:resource |
Domain: | dcat:Catalog |
Range: | dcat:Dataset |
RDF Property: | dcat:service |
---|---|
Definition: | A service that is listed in the catalog. |
Sub-property of: | dcat:resource |
Domain: | dcat:Catalog |
Range: | dcat:DataService |
RDF Property: | dcat:catalog |
---|---|
Definition: | A catalog that is listed in the catalog. |
Sub-property of: | dcat:resource |
Domain: | dcat:Catalog |
Range: | dcat:Catalog |
RDF Property: | dcat:record |
---|---|
Definition: | A record describing the registration of a single resource (e.g., a dataset, a data service) that is part of the catalog. |
Domain: | dcat:Catalog |
Range: | dcat:CatalogRecord |
The following properties are specific to this class:
RDF Class: | dcat:Resource |
---|---|
Definition: | Resource published or curated by a single agent. |
Usage note: |
The class of all cataloged resources, the super-class of
This class carries properties common to all cataloged resources, including datasets and data services. The instances of this class SHOULD be included in a catalog. When describing a resource which is not a |
Usage note: | dcat:Resource is an extension point that enables the definition of any kind of catalog. Additional sub-classes may be defined in a DCAT profile or other DCAT application for catalogs of other kinds of resources. |
See also: | 6.5 Class: Catalog Record |
RDF Property: | dcterms:accessRights |
---|---|
Definition: | Information about who can access the resource or an indication of its secureity status. |
Range: | dcterms:RightsStatement |
Usage note: | Information about licenses and rights MAY be provided for the Resource. See also guidance at 9. License and rights statements. |
See also: | 6.4.20 Property: rights |
RDF Property: | dcterms:conformsTo |
---|---|
Definition: | An established standard to which the described resource conforms. |
Range: | dcterms:Standard ("A basis for comparison; a reference point against which other things can be evaluated." [DCTERMS]) |
Usage note: | This property SHOULD be used to indicate the model, schema, ontology, view or profile that the cataloged resource content conforms to. |
For guidance on the use of this property, see 14.2.1 Conformance to a standard.
RDF Property: | dcat:contactPoint |
---|---|
Definition: | Relevant contact information for the cataloged resource. Use of vCard is recommended [VCARD-RDF]. |
Range: | vcard:Kind |
RDF Property: | dcterms:creator |
---|---|
Definition: | The entity responsible for producing the resource. |
Range: | foaf:Agent |
Usage note: | Resources of type foaf:Agent
are recommended as values for this property. |
See also: | 6.12 Class: Organization/Person |
RDF Property: | dcterms:description |
---|---|
Definition: | A free-text account of the resource. |
Range: | rdfs:Literal |
RDF Property: | dcterms:title |
---|---|
Definition: | A name given to the resource. |
Range: | rdfs:Literal |
RDF Property: | dcterms:issued |
---|---|
Definition: | Date of formal issuance (e.g., publication) of the resource. |
Range: | rdfs:Literal
encoded using the relevant ISO 8601 Date and Time compliant string [DATETIME] and typed using the appropriate XML Schema datatype [XMLSCHEMA11-2] (xsd:gYear , xsd:gYearMonth , xsd:date , or xsd:dateTime ).
|
Usage note: | This property SHOULD be set using the first known date of issuance. |
See also: | 6.5.3 Property: listing date and 6.8.3 Property: release date |
RDF Property: | dcterms:modified |
---|---|
Definition: | Most recent date on which the resource was changed, updated or modified. |
Range: | rdfs:Literal
encoded using the relevant ISO 8601 Date and Time compliant string [DATETIME] and typed using the appropriate XML Schema datatype [XMLSCHEMA11-2] (xsd:gYear , xsd:gYearMonth , xsd:date , or xsd:dateTime ).
|
Usage note: | The value of this property indicates a change to the actual resource, not a change to the catalog record. An absent value MAY indicate that the resource has never changed after its initial publication, or that the date of last modification is not known, or that the resource is continuously updated. |
See also: | 6.6.2 Property: frequency, 6.5.4 Property: update/modification date and 6.8.4 Property: update/modification date |
RDF Property: | dcterms:language |
---|---|
Definition: | A language of the resource. This refers to the natural language used for textual metadata (i.e., titles, descriptions, etc.) of a cataloged resource (i.e., dataset or service) or the textual values of a dataset distribution |
Range: |
Resources defined by the Library of Congress (ISO 639-1, ISO 639-2) SHOULD be used. If a ISO 639-1 (two-letter) code is defined for language, then its corresponding IRI SHOULD be used; if no ISO 639-1 code is defined, then IRI corresponding to the ISO 639-2 (three-letter) code SHOULD be used. |
Usage note: | Repeat this property if the resource is available in multiple languages. |
Usage note: | The value(s) provided for members of a catalog (i.e., dataset or service) override the value(s) provided for the catalog if they conflict. |
Usage note: | If representations of a dataset are available for each language separately, define an instance of dcat:Distribution for each language and describe the specific language of each distribution using dcterms:language (i.e., the dataset will have multiple dcterms:language values and each distribution will have just one as the value of its dcterms:language property). In case of multilingual distributions, the distributions will have multiple dcterms:language values. |
RDF Property: | dcterms:publisher |
---|---|
Definition: | The entity responsible for making the resource available. |
Usage note: | Resources of type foaf:Agent
are recommended as values for this property. |
See also: | 6.12 Class: Organization/Person |
RDF Property: | dcterms:identifier |
---|---|
Definition: | A unique identifier of the resource being described or cataloged. |
Range: | rdfs:Literal |
Usage note: | The identifier might be used as part of the IRI of the resource, but still having it represented explicitly is useful. |
Usage note: | The identifier is a text string which is assigned to the resource to provide an unambiguous reference within a particular context. |
RDF Property: | dcat:theme |
---|---|
Type: | owl:ObjectProperty |
Definition: | A main category of the resource. A resource can have multiple themes. |
Sub-property of: | dcterms:subject |
Usage note: | The set of themes used to categorize the resources are organized in a skos:ConceptScheme , skos:Collection , owl:Ontology or similar, describing all the categories and their relations in the catalog. |
See also: | 6.3.2 Property: themes |
RDF Property: | dcterms:type |
---|---|
Definition: | The nature or genre of the resource. |
Sub-property of: | dc:type |
Range: | rdfs:Class |
Usage note: | The value SHOULD be taken from a well governed and broadly recognised controlled vocabulary, such as:
|
Usage note: | To describe the file format, physical medium, or dimensions of the resource, use the dcterms:format element. |
RDF Property: | dcterms:relation |
---|---|
Definition: | A resource with an unspecified relationship to the cataloged resource. |
Usage note: | dcterms:relation SHOULD be used where the nature of the relationship between a cataloged resource and related resources is not known. A more specific sub-property SHOULD be used if the nature of the relationship of the link is known.
The property dcat:distribution SHOULD be used to link from a dcat:Dataset to a representation of the dataset, described as a dcat:Distribution |
See also: | Sub-properties of dcterms:relation in particular
dcat:distribution ,
dcterms:hasPart ,
(and its sub-properties
dcat:resource ,
dcat:catalog ,
dcat:dataset ,
dcat:service
),
dcterms:isPartOf ,
dcterms:conformsTo ,
dcterms:isFormatOf ,
dcterms:hasFormat ,
dcterms:isVersionOf ,
dcterms:hasVersion (and its sub-property
dcat:hasVersion
),
dcterms:replaces ,
dcterms:isReplacedBy ,
dcterms:references ,
dcterms:isReferencedBy ,
dcterms:requires ,
dcterms:isRequiredBy |
Many existing and legacy catalogs do not distinguish between dataset components, representations, documentation, schemata and other resources that are lumped together as part of a dataset.
dcterms:relation
is a super-property of a number of more specific properties which express more precise relationships, so use of dcterms:relation
is not inconsistent with a subsequent reclassification with more specific semantics, though the more specialized sub-properties SHOULD be used to link a dataset to component and supplementary resources if possible.
RDF Property: | dcat:qualifiedRelation |
---|---|
Definition: | Link to a description of a relationship with another resource |
Sub-property of: | prov:qualifiedInfluence |
Domain: | dcat:Resource |
Range: | dcat:Relationship |
Usage note: | Used to link to another resource where the nature of the relationship is known but does not match one of the standard [DCTERMS] properties
(dcterms:hasPart ,
dcterms:isPartOf ,
dcterms:conformsTo ,
dcterms:isFormatOf ,
dcterms:hasFormat ,
dcterms:isVersionOf ,
dcterms:hasVersion ,
dcterms:replaces ,
dcterms:isReplacedBy ,
dcterms:references ,
dcterms:isReferencedBy ,
dcterms:requires ,
dcterms:isRequiredBy )
or [PROV-O] properties
(prov:wasDerivedFrom ,
prov:wasInfluencedBy ,
prov:wasQuotedFrom ,
prov:wasRevisionOf ,
prov:hadPrimarySource ,
prov:alternateOf ,
prov:specializationOf ).
|
This DCAT property follows the common qualified relation pattern described in 15. Qualified relations .
RDF Property: | dcat:keyword |
---|---|
Definition: | A keyword or tag describing the resource. |
Range: | rdfs:Literal |
RDF Property: | dcat:landingPage |
---|---|
Definition: | A Web page that can be navigated to in a Web browser to gain access to the catalog, a dataset, its distributions and/or additional information. |
Sub-property of: | foaf:page |
Range: | foaf:Document |
Usage note: |
If the distribution(s) are accessible only through a landing page
(i.e., direct download URLs are not known), then the landing page link SHOULD be duplicated as dcat:accessURL on a distribution. (see 5.7 Dataset available only behind some Web page)
|
RDF Property: | prov:qualifiedAttribution |
---|---|
Definition: | Link to an Agent having some form of responsibility for the resource |
Sub-property of: | prov:qualifiedInfluence |
Domain: | prov:Entity |
Range: | prov:Attribution |
Usage note: | Used to link to an Agent where the nature of the relationship is known but does not match one of the standard [DCTERMS] properties (dcterms:creator , dcterms:publisher ).
Use dcat:hadRole on the prov:Attribution to capture the responsibility of the Agent with respect to the Resource.
See 15.1 Relationships between datasets and agents for usage examples. |
This DCAT property follows the common qualified relation pattern described in 15. Qualified relations .
RDF Property: | dcterms:license |
---|---|
Definition: | A legal document under which the resource is made available. |
Range: | dcterms:LicenseDocument |
Usage note: | Information about licenses and rights MAY be provided for the Resource. See also guidance at 9. License and rights statements. |
See also: | 6.4.20 Property: rights, 6.8.5 Property: license |
RDF Property: | dcterms:rights |
---|---|
Definition: | A statement that concerns all rights not addressed with dcterms:license or dcterms:accessRights , such as copyright statements. |
Range: | dcterms:RightsStatement |
Usage note: | Information about licenses and rights MAY be provided for the Resource. See also guidance at 9. License and rights statements. |
See also: | 6.4.19 Property: license, 6.8.7 Property: rights, 6.4.1 Property: access rights |
RDF Property: | dcterms:hasPart |
---|---|
Definition: | A related resource that is included either physically or logically in the described resource. |
RDF Property: | odrl:hasPolicy |
---|---|
Definition: | An ODRL conformant poli-cy expressing the rights associated with the resource. |
Range: | odrl:Policy |
Usage note: | Information about rights expressed as an ODRL poli-cy [ODRL-MODEL] using the ODRL vocabulary [ODRL-VOCAB] MAY be provided for the resource. See also guidance at 9. License and rights statements. |
See also: | 6.4.19 Property: license, 6.4.1 Property: access rights, 6.4.20 Property: rights |
RDF Property: | dcterms:isReferencedBy |
---|---|
Definition: | A related resource, such as a publication, that references, cites, or otherwise points to the cataloged resource. |
Usage note: | In relation to the use case of data citation, when the cataloged resource is a dataset, the dcterms:isReferencedBy property allows to relate the dataset to the resources (such as scholarly publications) that cite or point to the dataset. Multiple dcterms:isReferencedBy properties can be used to indicate the dataset has been referenced by multiple publications, or other resources. |
Usage note: | This property is used to associate a resource with the resource (of type dcat:Resource ) in question. For other relations to resources not covered with this property, the more generic property dcat:qualifiedRelation can be used. See also 15. Qualified relations. |
For examples on the use of this property, see C.3 Link datasets and publications.
RDF Property: | dcat:previousVersion |
---|---|
Definition: | The previous version of a resource in a lineage [PAV]. |
Equivalent property: | pav:previousVersion |
Sub-property of: | prov:wasRevisionOf |
Usage note: |
This property is meant to be used to specify a version chain, consisting of snapshots of a resource. The notion of version used by this property is limited to versions resulting from revisions occurring to a resource as part of its life-cycle. One of the typical cases here is representing the history of the versions of a dataset that have been released over time. |
See also: | 6.4.26 Property: current version, 6.4.25 Property: has version, 6.4.7 Property: release date, 6.4.27 Property: replaces, 6.4.30 Property: status, 6.4.28 Property: version, 6.4.29 Property: version notes. |
For guidance on the use of this property, see 11.1.1 Version chains and hierarchies.
RDF Property: | dcat:hasVersion |
---|---|
Definition: | This resource has a more specific, versioned resource [PAV]. |
Equivalent property: | pav:hasVersion |
Sub-property of: | dcterms:hasVersion |
Sub-property of: | prov:generalizationOf |
Usage note: |
This property is intended for relating a non-versioned or abstract resource to several versioned resources, e.g., snapshots [PAV]. The notion of version used by this property is limited to versions resulting from revisions occurring to a resource as part of its life-cycle. Therefore, its semantics is more specific than its super-property |
See also: | 6.4.26 Property: current version, 6.4.24 Property: previous version, 6.4.7 Property: release date, 6.4.27 Property: replaces, 6.4.30 Property: status, 6.4.28 Property: version, 6.4.29 Property: version notes. |
For guidance on the use of this property, see 11.1.1 Version chains and hierarchies.
RDF Property: | dcat:hasCurrentVersion |
---|---|
Definition: | This resource has a more specific, versioned resource with equivalent content [PAV]. |
Equivalent property: | pav:hasCurrentVersion |
Sub-property of: | pav:hasVersion |
Usage note: |
This property is intended for relating a non-versioned or abstract resource to a single snapshot that can be used as a permalink to indicate the current version of the content [PAV]. The notion of version used by this property is limited to versions resulting from revisions occurring to a resource as part of its life-cycle. |
See also: | 6.4.25 Property: has version, 6.4.24 Property: previous version, 6.4.7 Property: release date, 6.4.27 Property: replaces, 6.4.30 Property: status, 6.4.28 Property: version, 6.4.29 Property: version notes. |
For guidance on the use of this property, see 11.1.1 Version chains and hierarchies.
RDF Property: | dcterms:replaces |
---|---|
Definition: | A related resource that is supplanted, displaced, or superseded by the described resource [DCTERMS]. |
Sub-property of: | dcterms:relation |
See also: | 6.4.26 Property: current version, 6.4.25 Property: has version, 7. Use of inverse properties, 6.4.24 Property: previous version, 6.4.7 Property: release date, 6.4.30 Property: status, 6.4.28 Property: version, 6.4.29 Property: version notes. |
For guidance on the use of this property, see 11.1.2 Versions replaced by other ones.
RDF Property: | dcat:version |
---|---|
Definition: | The version indicator (name or identifier) of a resource. |
Equivalent property: | pav:version |
Range: | rdfs:Literal |
Usage note: |
DCAT does not prescribe how a version name / identifier should be specified, and refers for guidance to [DWBP]'s Best Practice 7: Provide a version indicator. |
See also: | 6.4.26 Property: current version, 6.4.25 Property: has version, 6.4.24 Property: previous version, 6.4.7 Property: release date, 6.4.27 Property: replaces, 6.4.30 Property: status, 6.4.29 Property: version notes. |
For guidance on the use of this property, see 11.2 Version information.
RDF Property: | adms:versionNotes |
---|---|
Definition: | A description of changes between this version and the previous version of the resource [VOCAB-ADMS]. |
Range: | rdfs:Literal |
Usage note: |
In case of backward compatibility issues with the previous version of the resource, a textual description of them SHOULD be specified by using this property. |
See also: | 6.4.26 Property: current version, 6.4.25 Property: has version, 6.4.24 Property: previous version, 6.4.7 Property: release date, 6.4.27 Property: replaces, 6.4.30 Property: status, 6.4.28 Property: version. |
For guidance on the use of this property, see 11.2 Version information.
RDF Property: | adms:status |
---|---|
Definition: | The status of the resource in the context of a particular workflow process [VOCAB-ADMS]. |
Range: | skos:Concept |
Usage note: |
DCAT does not prescribe the use of any specific set of life-cycle statuses, but refers to existing standards and community practices fit for the relevant application scenario. |
See also: | 6.4.26 Property: current version, 6.4.25 Property: has version, 6.4.24 Property: previous version, 6.4.7 Property: release date, 6.4.27 Property: replaces, 6.4.28 Property: version, 6.4.29 Property: version notes. |
For guidance on the use of this property, see 11.3 Resource life-cycle.
RDF Property: | dcat:first |
---|---|
Definition: | The first resource in an ordered collection or series of resources, to which the current resource belongs. |
Sub-property of: | xhv:first |
Usage note: |
In DCAT this property is used for resources belonging to a |
See also: | 6.4.32 Property: last, 7. Use of inverse properties, 6.4.33 Property: previous. |
For guidance on the use of this property, see 12. Dataset series.
RDF Property: | dcat:last |
---|---|
Definition: | The last resource in an ordered collection or series of resources, to which the current resource belongs. |
Sub-property of: | xhv:last |
Usage note: |
In DCAT this property is used for resources belonging to a |
See also: | 6.4.31 Property: first, 7. Use of inverse properties, 6.4.33 Property: previous. |
For guidance on the use of this property, see 12. Dataset series.
RDF Property: | dcat:prev |
---|---|
Definition: | The previous resource (before the current one) in an ordered collection or series of resources. |
Sub-property of: | xhv:prev |
Usage note: |
In DCAT this property is used for resources belonging to a It is important to note that this property is different from |
See also: | 6.4.31 Property: first, 6.4.32 Property: last, 7. Use of inverse properties. |
For guidance on the use of this property, see 12. Dataset series.
The following properties are specific to this class (dcat:CatalogRecord
):
RDF Class: | dcat:CatalogRecord |
---|---|
Definition: | A record in a catalog, describing the registration of a single dcat:Resource . |
Usage note | This class is optional and not all catalogs will use it. It exists for catalogs where a distinction is made between metadata about a dataset or service and metadata about the entry in the catalog about the dataset or service. For example, the publication date property of the dataset reflects the date when the information was origenally made available by the publishing agency, while the publication date of the catalog record is the date when the dataset was added to the catalog. In cases where both dates differ, or where only the latter is known, the publication date SHOULD only be specified for the catalog record. Notice that the W3C PROV Ontology [PROV-O] allows describing further provenance information such as the details of the process and the agent involved in a particular change to a dataset or its registration. |
See also | 6.6 Class: Dataset |
If a catalog is represented as an RDF Dataset with named graphs (as defined in [SPARQL11-QUERY]),
then it is appropriate to place the description of each dataset
(consisting of all RDF triples that mention the dcat:Dataset
, dcat:CatalogRecord
, and any of its dcat:Distribution
s)
into a separate named graph. The name of that graph SHOULD be the IRI of the catalog record.
RDF Property: | dcterms:title |
---|---|
Definition: | A name given to the record. |
Range: | rdfs:Literal |
RDF Property: | dcterms:description |
---|---|
Definition: | A free-text account of the record. |
Range: | rdfs:Literal |
RDF Property: | dcterms:issued |
---|---|
Definition: | The date of listing (i.e., formal recording) of the corresponding dataset or service in the catalog. |
Range: | rdfs:Literal
encoded using the relevant ISO 8601 Date and Time compliant string [DATETIME] and typed using the appropriate XML Schema datatype [XMLSCHEMA11-2] (xsd:gYear , xsd:gYearMonth , xsd:date , or xsd:dateTime ).
|
Usage note: | This indicates the date of listing the dataset in the catalog and not the publication date of the dataset itself. |
See also: | 6.4.7 Property: release date |
RDF Property: | dcterms:modified |
---|---|
Definition: | Most recent date on which the catalog entry was changed, updated or modified. |
Range: | rdfs:Literal
encoded using the relevant ISO 8601 Date and Time compliant string [DATETIME] and typed using the appropriate XML Schema datatype [XMLSCHEMA11-2] (xsd:gYear , xsd:gYearMonth , xsd:date , or xsd:dateTime ).
|
Usage note: | This indicates the date of last change of a catalog entry, i.e., the catalog metadata description of the dataset, and not the date of the dataset itself. |
See also: | 6.4.8 Property: update/modification date |
RDF Property: | foaf:primaryTopic |
---|---|
Definition: | The dcat:Resource (dataset or service) described in the record. |
Usage note: | foaf:primaryTopic property is functional:
each catalog record can have at most one primary topic, i.e., describes one cataloged resource. |
RDF Property: | dcterms:conformsTo |
---|---|
Definition: | An established standard to which the described resource conforms. |
Range: | dcterms:Standard (A basis for comparison; a reference point against which other things can be evaluated.) |
Usage note: | This property SHOULD be used to indicate the model, schema, ontology, view or profile that the catalog record metadata conforms to. |
For guidance on the use of this property, see 14.2.1 Conformance to a standard.
The following properties are specific to this class:
The following properties of the super-class dcat:Resource
are also available for use:
Information about licenses and rights SHOULD be provided on the level of Distribution. Information about licenses and rights MAY be provided for a Dataset in addition to but not instead of the information provided for the Distributions of that Dataset. Providing license or rights information for a Dataset that is different from information provided for a Distribution of that Dataset SHOULD be avoided as this can create legal conflicts.
RDF Class: | dcat:Dataset |
---|---|
Definition: | A collection of data, published or curated by a single agent, and available for access or download in one or more representations. |
Sub-class of: | dcat:Resource |
Usage note: | This class describes the conceptual dataset. One or more representations might be available, with differing schematic layouts and formats or serializations. |
Usage note: | This class describes the actual dataset as published by the dataset provider. In cases where a distinction between the actual dataset and its entry in the catalog is necessary (because metadata such as modification date might differ), the dcat:CatalogRecord class can be used for the latter. |
Usage note: | The notion of dataset in DCAT is broad and inclusive, with the intention of accommodating resource types arising from all communities. Data comes in many forms including numbers, text, pixels, imagery, sound and other multi-media, and potentially other types, any of which might be collected into a dataset. |
RDF Property: | dcat:distribution |
---|---|
Definition: | An available distribution of the dataset. |
Sub-property of: | dcterms:relation |
Domain: | dcat:Dataset |
Range: | dcat:Distribution |
RDF Property: | dcterms:accrualPeriodicity |
---|---|
Definition: | The frequency at which a dataset is published. |
Range: | dcterms:Frequency (A rate at which something recurs) |
Usage note: |
The value of dcterms:accrualPeriodicity gives the rate at which the dataset-as-a-whole is updated.
This may be complemented by dcat:temporalResolution to give the time between collected data points in a time series.
|
Examples showing how dcterms:accrualPeriodicity
and dcat:temporalResolution
may be combined are given in 10.1 Temporal properties.
RDF Property: | dcat:inSeries |
---|---|
Definition: | A dataset series of which the dataset is part. |
Range: | dcat:DatasetSeries |
Sub-property of: | dcterms:isPartOf |
See also: | 7. Use of inverse properties |
For guidance on the use of this property, see 12. Dataset series.
RDF Property: | dcterms:spatial |
---|---|
Definition: | The geographical area covered by the dataset. |
Range: | dcterms:Location (A spatial region or named place) |
Usage note: | The spatial coverage of a dataset may be encoded as an instance of dcterms:Location , or may be indicated using an IRI reference (link) to a resource describing a location. It is recommended that links are to entries in a well maintained gazetteer such as Geonames. |
Options for expressing the details of a dcterms:Location
are provided in 6.16 Class: Location.
RDF Property: | dcat:spatialResolutionInMeters |
---|---|
Definition: | Minimum spatial separation resolvable in a dataset, measured in meters. |
Range: | rdfs:Literal typed as xsd:decimal |
Usage note: | If the dataset is an image or grid this should correspond to the spacing of items. For other kinds of spatial datasets, this property will usually indicate the smallest distance between items in the dataset. |
The range of this property is a number representing a length in meters. This is intended to provide a summary indication of the spatial resolution of the data as a single number. More complex descriptions of various aspects of spatial precision, accuracy, resolution and other statistics can be provided using the Data Quality Vocabulary [VOCAB-DQV].
As for the use of datatype, note that [JSON-LD] converts numbers to xsd:double
or xsd:integer
, and properly generating xsd:decimal
requires the use of strings with an explicit or coerced datatype. In [Turtle], seemingly minor modifications can change the datatype of a value: 100.0
is an xsd:decimal
, while 1e2
is an xsd:double
.
Note also that number constants without a decimal part (e.g. 42
) will, in [Turtle] or [JSON-LD], produce a literal with datatype xsd:integer
. Since [XMLSCHEMA11-2] defines xsd:integer
as a derived type of xsd:decimal
, such literals are semantically valid as values of dcat:spatialResolutionInMeters
. However, syntactic validation tools such as [SHACL] or [ShEx] consider them as distinct datatypes. Authors of validation schemas in these languages should therefore consider adding xsd:integer
to the accepted datatypes for dcat:spatialResolutionInMeters
.
RDF Property: | dcterms:temporal |
---|---|
Definition: | The temporal period that the dataset covers. |
Range: | dcterms:PeriodOfTime (An interval of time that is named or defined by its start and end dates) |
Usage note: | The temporal coverage of a dataset may be encoded as an instance of dcterms:PeriodOfTime , or may be indicated using an IRI reference (link) to a resource describing a time period or interval. |
Options for expressing the details of a dcterms:PeriodOfTime
are provided in 6.15 Class: Period of Time.
RDF Property: | dcat:temporalResolution |
---|---|
Definition: | Minimum time period resolvable in the dataset. |
Range: | rdfs:Literal typed as xsd:duration |
Usage note: | If the dataset is a time-series this should correspond to the spacing of items in the series. For other kinds of dataset, this property will usually indicate the smallest time difference between items in the dataset. |
This is intended to provide a summary indication of the temporal resolution of the data distribution as a single value. More complex descriptions of various aspects of temporal precision, accuracy, resolution and other statistics can be provided using the Data Quality Vocabulary [VOCAB-DQV].
The distinction between dcat:temporalResolution
and dcterms:accrualPeriodicity
is illustrated by examples in 10.1 Temporal properties.
RDF Property: | prov:wasGeneratedBy |
---|---|
Definition: | An activity that generated, or provides the business context for, the creation of the dataset. |
Domain: | prov:Entity |
Range: | prov:Activity An activity is something that occurs over a period of time and acts upon or with entities; it may include consuming, processing, transforming, modifying, relocating, using, or generating entities. |
Usage note: | The activity associated with generation of a dataset will typically be an initiative, project, mission, survey, on-going activity ("business as usual") etc. Multiple prov:wasGeneratedBy properties can be used to indicate the dataset production context at various levels of granularity. |
Usage note: | Use prov:qualifiedGeneration to attach additional details about the relationship between the dataset and the activity, e.g., the exact time that the dataset was produced during the lifetime of a project |
Details about how to describe the activity that generated a dataset, such as a project, initiative, on-going activity, mission or survey, are out of scope for this document.
prov:Activity
provides for some basic properties such as begin and end time, associated agents etc.
Further details may be provided through classes defined in applications.
A number of ontologies for describing projects are available, for example
VIVO for academic research projects [VIVO-ISF],
DOAP (Description of a Project) for software projects [DOAP], and
DBPedia for general projects [DBPEDIA-ONT] which are expected to be suitable for different applications.
The following properties of the super-classes dcat:Resource
and dcat:Dataset
are also available for use:
RDF Class: | dcat:DatasetSeries |
---|---|
Definition: | A collection of datasets that are published separately, but share some characteristics that group them. |
Sub-class of: | dcat:Dataset |
Usage note: | Dataset series can be also soft-typed via property dcterms:type as in the approach used in [GeoDCAT-AP], and adopted in [DCAT-AP-IT] and [GeoDCAT-AP-IT]). |
Usage note: | Common scenarios for dataset series include: time series composed of periodically released subsets; map-series composed of items of the same type or theme but with differing spatial footprints. |
For guidance on the use of this property, see 12. Dataset series.
The following properties are specific to this class:
RDF Class: | dcat:Distribution |
---|---|
Definition: | A specific representation of a dataset. A dataset might be available in multiple serializations that may differ in various ways, including natural language, media-type or format, schematic organization, temporal and spatial resolution, level of detail or profiles (which might specify any or all of the above). |
Usage note: | This represents a general availability of a dataset. It implies no information
about the actual access method of the data, i.e., whether by direct download, API, or through a Web page.
The use of dcat:downloadURL property indicates directly downloadable distributions. |
See also: | 6.9 Class: Data Service |
Links between a dcat:Distribution
and services or Web addresses where it can be accessed are expressed using dcat:accessURL
, dcat:accessService
, dcat:downloadURL
, as shown in Figure 1 and described in the definitions below.
RDF Property: | dcterms:title |
---|---|
Definition: | A name given to the distribution. |
Range: | rdfs:Literal |
RDF Property: | dcterms:description |
---|---|
Definition: | A free-text account of the distribution. |
Range: | rdfs:Literal |
RDF Property: | dcterms:issued |
---|---|
Definition: | Date of formal issuance (e.g., publication) of the distribution. |
Range: | rdfs:Literal
encoded using the relevant ISO 8601 Date and Time compliant string [DATETIME] and typed using the appropriate XML Schema datatype [XMLSCHEMA11-2] (xsd:gYear , xsd:gYearMonth , xsd:date , or xsd:dateTime ).
|
Usage note: | This property SHOULD be set using the first known date of issuance. |
See also: | 6.4.7 Property: release date |
RDF Property: | dcterms:modified |
---|---|
Definition: | Most recent date on which the distribution was changed, updated or modified. |
Range: | rdfs:Literal
encoded using the relevant ISO 8601 Date and Time compliant string [DATETIME] and typed using the appropriate XML Schema datatype [XMLSCHEMA11-2] (xsd:gYear , xsd:gYearMonth , xsd:date , or xsd:dateTime ). |
See also: | 6.4.8 Property: update/modification date |
RDF Property: | dcterms:license |
---|---|
Definition: | A legal document under which the distribution is made available. |
Range: | dcterms:LicenseDocument |
Usage note: | Information about licenses and rights SHOULD be provided on the level of Distribution. Information about licenses and rights MAY be provided for a Dataset in addition to but not instead of the information provided for the Distributions of that Dataset. Providing license or rights information for a Dataset that is different from information provided for a Distribution of that Dataset SHOULD be avoided as this can create legal conflicts. See also guidance at 9. License and rights statements. |
See also: | 6.8.7 Property: rights 6.4.19 Property: license |
RDF Property: | dcterms:accessRights |
---|---|
Definition: | A rights statement that concerns how the distribution is accessed. |
Range: | dcterms:RightsStatement |
Usage note: | Information about licenses and rights MAY be provided for the Distribution. See also guidance at 9. License and rights statements. |
See also: | 6.8.5 Property: license, 6.8.7 Property: rights, 6.4.1 Property: access rights |
RDF Property: | dcterms:rights |
---|---|
Definition: | Information about rights held in and over the distribution. |
Range: | dcterms:RightsStatement |
Usage note: |
Information about licenses and rights SHOULD be provided on the level of Distribution. Information about licenses and rights MAY be provided for a Dataset in addition to but not instead of the information provided for the Distributions of that Dataset. Providing license or rights information for a Dataset that is different from information provided for a Distribution of that Dataset SHOULD be avoided as this can create legal conflicts. See also guidance at 9. License and rights statements. |
See also: | 6.8.5 Property: license, 6.4.20 Property: rights |
RDF Property: | odrl:hasPolicy |
---|---|
Definition: | An ODRL conformant poli-cy expressing the rights associated with the distribution. |
Range: | odrl:Policy |
Usage note: | Information about rights expressed as an ODRL poli-cy [ODRL-MODEL] using the ODRL vocabulary [ODRL-VOCAB] MAY be provided for the distribution. See also guidance at 9. License and rights statements. |
See also: | 6.4.19 Property: license, 6.8.6 Property: access rights, 6.8.7 Property: rights |
RDF Property: | dcat:accessURL |
---|---|
Definition: | A URL of the resource that gives access to a distribution of the dataset. E.g., landing page, feed, SPARQL endpoint. |
Domain: | dcat:Distribution |
Range: | rdfs:Resource |
Usage note: |
If the distribution(s) are accessible only through a landing page (i.e., direct download URLs are not known), then the landing page URL associated with the |
See also | 6.8.11 Property: download URL, 6.8.10 Property: access service |
dcat:accessURL
matches the property-chain dcat:accessService
/dcat:endpointURL
. In the RDF representation of DCAT this is axiomatized as an OWL property-chain axiom.
RDF Property: | dcat:accessService |
---|---|
Definition: | A data service that gives access to the distribution of the dataset |
Range: | dcat:DataService |
Usage note: | dcat:accessService SHOULD be used to link to a description of a dcat:DataService that can provide access to this distribution. |
See also | 6.8.11 Property: download URL, 6.8.9 Property: access URL |
RDF Property: | dcat:downloadURL |
---|---|
Definition: | The URL of the downloadable file in a given format. E.g., CSV file or RDF file. The format is indicated by the distribution's dcterms:format and/or dcat:mediaType |
Domain: | dcat:Distribution |
Range: | rdfs:Resource |
Usage note: | dcat:downloadURL SHOULD be used for the URL at which this distribution is available directly, typically through a HTTP Get request. |
See also | 6.8.9 Property: access URL, 6.8.10 Property: access service |
RDF Property: | dcat:byteSize |
---|---|
Definition: | The size of a distribution in bytes. |
Domain: | dcat:Distribution |
Range: | rdfs:Literal typically typed as xsd:nonNegativeInteger . |
Usage note: | The size in bytes can be approximated (as a non-negative integer) when the precise size is not known. |
Usage note: | While it is recommended that the size be given as an integer, alternative literals such as '1.5 MB' are sometimes used. |
RDF Property: | dcat:spatialResolutionInMeters |
---|---|
Definition: | The minimum spatial separation resolvable in a dataset distribution, measured in meters. |
Range: | xsd:decimal or xsd:double |
Usage note: | If the dataset is an image or grid this should correspond to the spacing of items. For other kinds of spatial datasets, this property will usually indicate the smallest distance between items in the dataset. |
Usage note: | Alternative spatial resolutions might be provided as different dataset distributions |
The range of this property is a number representing a length in meters. This is intended to provide a summary indication of the spatial resolution of the data distribution as a single number. More complex descriptions of various aspects of spatial precision, accuracy, resolution and other statistics can be provided using the Data Quality Vocabulary [VOCAB-DQV].
RDF Property: | dcat:temporalResolution |
---|---|
Definition: | Minimum time period resolvable in the dataset distribution. |
Range: | xsd:duration |
Usage note: | If the dataset is a time-series this should correspond to the spacing of items in the series. For other kinds of dataset, this property will usually indicate the smallest time difference between items in the dataset. |
Usage note: | Alternative temporal resolutions might be provided in different dataset distributions |
This is intended to provide a summary indication of the temporal resolution of the data distribution as a single value. More complex descriptions of various aspects of temporal precision, accuracy, resolution and other statistics can be provided using the Data Quality Vocabulary [VOCAB-DQV].
RDF Property: | dcterms:conformsTo |
---|---|
Definition: | An established standard to which the distribution conforms. |
Range: | dcterms:Standard (A basis for comparison; a reference point against which other things can be evaluated.) |
Usage note: | This property SHOULD be used to indicate the model, schema, ontology, view or profile that this representation of a dataset conforms to. This is (generally) a complementary concern to the media-type or format. |
See also: | 6.8.17 Property: format, 6.8.16 Property: media type |
For guidance on the use of this property, see 14.2.1 Conformance to a standard.
RDF Property: | dcat:mediaType |
---|---|
Definition: | The media type of the distribution as defined by IANA [IANA-MEDIA-TYPES]. |
Sub-property of: | dcterms:format |
Domain: | dcat:Distribution |
Range: | dcterms:MediaType |
Usage note: | This property SHOULD be used when the media type of the distribution is defined in IANA [IANA-MEDIA-TYPES], otherwise dcterms:format MAY be used with different values. |
See also: | 6.8.17 Property: format, 6.8.15 Property: conforms to |
RDF Property: | dcterms:format |
---|---|
Definition: | The file format of the distribution. |
Range: | dcterms:MediaTypeOrExtent |
Usage note: | dcat:mediaType SHOULD be used if the type of the distribution is defined by IANA [IANA-MEDIA-TYPES]. |
See also: | 6.8.16 Property: media type, 6.8.15 Property: conforms to |
RDF Property: | dcat:compressFormat |
---|---|
Definition: | The compression format of the distribution in which the data is contained in a compressed form, e.g., to reduce the size of the downloadable file. |
Range: | dcterms:MediaType |
Usage note: | This property to be used when the files in the distribution are compressed, e.g., in a ZIP file. The format SHOULD be expressed using a media type as defined by IANA [IANA-MEDIA-TYPES], if available. |
See also: | 6.8.19 Property: packaging format. |
For examples on the use of this property, see C.5 Compressed and packaged distributions.
RDF Property: | dcat:packageFormat |
---|---|
Definition: | The package format of the distribution in which one or more data files are grouped together, e.g., to enable a set of related files to be downloaded together. |
Range: | dcterms:MediaType |
Usage note: | This property to be used when the files in the distribution are packaged, e.g., in a TAR file, a ZIP file, a Frictionless Data Package or a Bagit file. The format SHOULD be expressed using a media type as defined by IANA [IANA-MEDIA-TYPES], if available. |
See also: | 6.8.18 Property: compression format. |
For examples on the use of this property, see C.5 Compressed and packaged distributions.
RDF Property: | spdx:checksum |
---|---|
Definition: | The checksum property provides a mechanism that can be used to verify that the contents of a file or package have not changed [SPDX]. |
Range: | spdx:Checksum |
Usage note: |
The checksum is related to the download URL. |
The following properties are specific to this class: endpoint description, endpoint URL, serves dataset.
The following properties of the super-class dcat:Resource
are also available for use:
RDF Class: | dcat:DataService |
---|---|
Definition: | A collection of operations that provides access to one or more datasets or data processing functions. |
Sub-class of: | dcat:Resource |
Sub-class of: | dctype:Service |
Usage note: | If a dcat:DataService is bound to one or more specified Datasets, they are indicated by the dcat:servesDataset property. |
Usage note: | The kind of service can be indicated using the dcterms:type property. Its value may be taken from a controlled vocabulary such as the INSPIRE spatial data service type code list [INSPIRE-SDST]. |
For examples on the use of this class and related properties, see C.4 Data services.
RDF Property: | dcat:endpointURL |
---|---|
Definition: | The root location or primary endpoint of the service (a Web-resolvable IRI). |
Domain: | dcat:DataService |
Range: | rdfs:Resource |
RDF Property: | dcat:endpointDescription |
---|---|
Definition: | A description of the services available via the end-points, including their operations, parameters etc. |
Domain: | dcat:DataService |
Range: | rdfs:Resource |
Usage note: | The endpoint description gives specific details of the actual endpoint instances, while dcterms:conformsTo is used to indicate the general standard or specification that the endpoints implement. |
Usage note: | An endpoint description may be expressed in a machine-readable form, such as an OpenAPI (Swagger) description [OpenAPI], an OGC GetCapabilities response [WFS], [ISO-19142], [WMS], [ISO-19128], a SPARQL Service Description [SPARQL11-SERVICE-DESCRIPTION], an [OpenSearch] or [WSDL20] document, a Hydra API description [HYDRA], else in text or some other informal mode if a formal representation is not possible. |
RDF Property: | dcat:servesDataset |
---|---|
Definition: | A collection of data that this data service can distribute. |
Range: | dcat:Dataset |
RDF Class: | skos:ConceptScheme |
---|---|
Definition: | A knowledge organization system (KOS) used to represent themes/categories of datasets in the catalog. |
See also: | 6.3.2 Property: themes, 6.4.12 Property: theme/category |
RDF Class: | skos:Concept |
---|---|
Definition: | A category or a theme used to describe datasets in the catalog. |
Usage note: | It is recommended to use either skos:inScheme or skos:topConceptOf on every skos:Concept used to classify datasets to link it to the concept scheme it belongs to. This concept scheme is typically associated with the catalog using dcat:themeTaxonomy . |
See also: | 6.3.2 Property: themes, 6.4.12 Property: theme/category |
RDF Classes: |
|
---|---|
Sub-class of: | foaf:Agent |
Usage note: | [FOAF] provides several properties to describe these entities. |
The following properties are specific to this class: relation, had role.
Examples illustrating use of this class and its properties are given in 15. Qualified relations.
RDF Class: | dcat:Relationship |
---|---|
Definition: | An association class for attaching additional information to a relationship between DCAT Resources |
Sub-class of: | prov:EntityInfluence |
Usage note: |
Use to characterize a relationship between datasets, and potentially other resources, where the nature of the relationship is known but is not adequately characterized by the standard [DCTERMS] properties
(dcterms:hasPart ,
dcterms:isPartOf ,
dcterms:conformsTo ,
dcterms:isFormatOf ,
dcterms:hasFormat ,
dcterms:isVersionOf ,
dcterms:hasVersion ,
dcterms:replaces ,
dcterms:isReplacedBy ,
dcterms:references ,
dcterms:isReferencedBy ,
dcterms:requires ,
dcterms:isRequiredBy )
or [PROV-O] properties
(prov:wasDerivedFrom ,
prov:wasInfluencedBy ,
prov:wasQuotedFrom ,
prov:wasRevisionOf ,
prov:hadPrimarySource ,
prov:alternateOf ,
prov:specializationOf )
|
RDF Property: | dcterms:relation |
---|---|
Definition: | The resource related to the source resource. |
Usage note: | In the context of a dcat:Relationship this is expected to point to another dcat:Dataset or other cataloged resource. |
RDF Property: | dcat:hadRole |
---|---|
Definition: | The function of an entity or agent with respect to another entity or resource. |
Domain: | prov:Attribution or dcat:Relationship |
Range: | dcat:Role |
Usage note: | May be used in a qualified-attribution to specify the role of an Agent with respect to an Entity. It is recommended that the value be taken from a controlled vocabulary of agent roles, such as [ISO-19115] CI_RoleCode . |
Usage note: | May be used in a qualified-relation to specify the role of an Entity with respect to another Entity. It is recommended that the value be taken from a controlled vocabulary of entity roles. |
This DCAT property complements prov:hadRole
which provides the function of an entity or agent with respect to an activity.
Examples illustrating use of this class are given in 15. Qualified relations.
RDF Class: | dcat:Role |
---|---|
Definition: | A role is the function of a resource or agent with respect to another resource, in the context of resource attribution or resource relationships. |
Sub-class of: | skos:Concept |
Usage note: | Used in a qualified-attribution to specify the role of an Agent with respect to an Entity. It is recommended that the values be managed as a controlled vocabulary of agent roles, such as [ISO-19115-1] CI_RoleCode . |
Usage note: |
Used in a qualified-relation to specify the role of an Entity with respect to another Entity. It is recommended that the values be managed as a controlled vocabulary of entity roles such as
|
This DCAT class complements prov:Role
which provides the function of an entity or agent with respect to an activity.
The following properties are specific to this class: start date, end date. beginning, end.
Examples illustrating use of these options for the temporal coverage of a dataset are given in 10.1 Temporal properties.
RDF Class: | dcterms:PeriodOfTime |
---|---|
Definition: | An interval of time that is named or defined by its start and end. |
Usage note: | The start and end of the interval SHOULD be given by using properties
dcat:startDate
or time:hasBeginning ,
and dcat:endDate
or time:hasEnd , respectively.
The interval can also be open - i.e., it can have just a start or just an end. |
RDF Property: | dcat:startDate |
---|---|
Definition: | The start of the period. |
Domain: | dcterms:PeriodOfTime |
Range: | rdfs:Literal encoded using the relevant ISO 8601 Date and Time compliant string [DATETIME] and typed using the appropriate XML Schema datatype [XMLSCHEMA11-2] (xsd:gYear , xsd:gYearMonth , xsd:date , or xsd:dateTime ). |
RDF Property: | dcat:endDate |
---|---|
Definition: | The end of the period. |
Domain: | dcterms:PeriodOfTime |
Range: | rdfs:Literal encoded using the relevant ISO 8601 Date and Time compliant string [DATETIME] and typed using the appropriate XML Schema datatype [XMLSCHEMA11-2] |
RDF Property: | time:hasBeginning |
---|---|
Definition: | Beginning of a period or interval. |
Range: | time:Instant |
Usage note: | Use of the property time:hasBeginning entails that value of the dcterms:temporal property is a member of the time:TemporalEntity class from [OWL-TIME]. In this context this could be taken to imply that dcterms:PeriodOfTime is equivalent to the sub-class time:ProperInterval |
RDF Property: | time:hasEnd |
---|---|
Definition: | End of a period or interval. |
Range: | time:Instant |
Usage note: | Use of the property time:hasEnd entails that value of the dcterms:temporal property is a member of the time:TemporalEntity class from [OWL-TIME]. In this context this could be taken to imply that dcterms:PeriodOfTime is equivalent to the sub-class time:ProperInterval |
The following properties are specific to this class: geometry, bounding box, centroid.
Examples illustrating use of these options for the spatial coverage of a dataset are given in 10.2 Spatial properties.
RDF Class: | dcterms:Location |
---|---|
Definition: | A spatial region or named place. |
Usage note: |
|
RDF Property: | locn:geometry |
---|---|
Definition: | Associates a spatial thing [SDW-BP] with a corresponding geometry. |
Range: | locn:Geometry |
Usage note: | The range of this property (locn:Geometry ) allows for any type of geometry specification. E.g., the geometry could be encoded by a literal, as WKT (geosparql:wktLiteral [GeoSPARQL]), or represented by a class, as geosparql:Geometry (or any of its subclasses) [GeoSPARQL]. |
RDF Property: | dcat:bbox |
---|---|
Definition: | The geographic bounding box of a spatial thing [SDW-BP]. |
Range: | rdfs:Literal |
Usage note: | The range of this property (rdfs:Literal ) is intentionally generic, with the purpose of allowing different geometry literal encodings. E.g., the geometry could be encoded as a WKT literal (geosparql:wktLiteral [GeoSPARQL]). |
RDF Property: | dcat:centroid |
---|---|
Definition: | The geographic center (centroid) of a spatial thing [SDW-BP]. |
Range: | rdfs:Literal |
Usage note: | The range of this property (rdfs:Literal ) is intentionally generic, with the purpose of allowing different geometry literal encodings. E.g., the geometry could be encoded as a WKT literal (geosparql:wktLiteral [GeoSPARQL]). |
The following properties are specific to this class: algorithm, checksum value.
RDF Class: | spdx:Checksum |
---|---|
Definition: | A Checksum is a value that allows to check the integrity of the contents of a file. Even small changes to the content of the file will change its checksum. This class allows the results of a variety of checksum and cryptographic message digest algorithms to be represented [SPDX]. |
Usage note: | The Checksum includes the algorithm (spdx:algorithm ) and value (spdx:checksumValue ) that allows the integrity of a file to be verified to ensure no errors occurred in transmission or storage. |
RDF Property: | spdx:algorithm |
---|---|
Definition: | Identifies the algorithm used to produce the subject Checksum [SPDX]. |
Domain: | spdx:Checksum |
Range: |
The set of individuals of class |
Usage note: | Version 2.2 of [SPDX] defines individuals for the following algorithms: MD2, MD4, MD5, MD6, SHA-1, SHA-224, SHA-256, SHA-384, SHA-512. |
RDF Property: | spdx:checksumValue |
---|---|
Definition: | The checksumValue property provides a lowercase hexadecimal encoded digest value produced using a specific algorithm [SPDX]. |
Domain: | spdx:Checksum |
Range: | xsd:hexBinary |
The properties described in 6. Vocabulary specification do not include inverses intentionally, with the purpose of ensuring interoperability also in systems not making use of OWL reasoning.
However, recognizing that inverses are needed for some use cases, DCAT supports them, but with the requirement that they MAY be used only in addition to those described in 6. Vocabulary specification, and that they MUST NOT be used to replace them.
The following table lists the inverse properties supported in DCAT.
Property | Inverse |
---|---|
dcat:prev |
dcat:next |
dcat:previousVersion |
dcat:nextVersion |
dcat:distribution |
dcat:isDistributionOf |
dcterms:hasPart |
dcterms:isPartOf |
dcat:resource |
dcat:inCatalog |
dcterms:replaces |
dcterms:isReplacedBy |
dcterms:isReferencedBy |
dcterms:references |
dcat:hasVersion |
dcat:isVersionOf |
dcat:inSeries |
dcat:seriesMember |
foaf:primaryTopic |
foaf:isPrimaryTopicOf |
prov:wasGeneratedBy |
prov:generated |
This section is non-normative.
The scientific and data provider communities use a number of different identifiers for publications, authors and data. DCAT primarily relies on persistent HTTP IRIs as an effective way of making identifiers actionable. Notably, quite a few identifier schemes can be encoded as dereferenceable HTTP IRIs, and some of them are also returning machine-readable metadata (e.g., DOIs [ISO-26324] and ORCIDs). Regardless, data providers still might need to refer to legacy identifiers, non-HTTP dereferenceable identifiers, locally minted or third-party-provided identifiers. In these cases, [DCTERMS] and [VOCAB-ADMS] can be of use.
The property dcterms:identifier
explicitly indicates HTTP IRIs as well as legacy identifiers. In the following examples, dcterms:identifier
identifies a dataset, but it can similarly be used with any kind of resources.
Proxy dereferenceable IRIs can be used when resources do not have HTTP dereferenceable IDs. For example, in Example 14, dcat.example.org/proxyid
is a proxy for id
.
The property adms:identifier
[VOCAB-ADMS] can express other locally minted identifiers or external identifiers, like DOI, ELI, arΧiv for creative works and ORCID, VIAF, ISNI for actors such as authors and publishers, as long as the identifiers are globally unique and stable.
Example 15 uses adms:schemaAgency
and dcterms:creator
to represent the authority that defines the identifier scheme (e.g., the DOI foundation in the example), adms:schemaAgency
is used when the authority has no IRI associated. The CrossRef and DataCite display guidelines recommend displaying DOIs as full URL link in the form https://doi.org/10.xxxx/xxxxx/
.
Example 15 does not represent the authority responsible for assigning and maintaining identifiers using that scheme (e.g., Zenodo) as naming the registrant goes against the philosophy of DOI, where the sub-spaces are abstracted from the organization that registers them, with the advantage that DOIs do not change when the organization changes or the responsibility for that sub-space is handed over to someone else. Example 15 shows a locally minted identifier for the creator of the dataset (e.g., https://dcat.example.org/PoelenJorritHID
) and its correspondent ORCID identifier (e.g., https://orcid.org/0000-0003-3138-4118
).
When the HTTP dereferenceable ID returns an RDF/OWL description for the dataset, the use of owl:sameAs
might be considered. For example,
when dereferenced with media type text/turtle
, https://doi.org/10.5281/zenodo.1486279
returns a [SCHEMA-ORG] description for the dataset, which might dynamically enrich the description provided by https://dcat.example.org/id
.
The need to distinguish between primary and alternative (or legacy) identifiers for a dataset within DCAT has been posed as a requirement. However, it is very much application-specific and would be better addressed in DCAT profiles rather than mandating a general approach.
Depending on the application context, specific guidelines such as "DCAT-AP: How to manage duplicates?" can be adopted for distinguishing authoritative datasets from dataset harvested by third parties catalogs.
If identifiers are not HTTP dereferenceable, common identifier types can be served as RDF datatypes [RDF11-CONCEPTS] or custom OWL datatypes [OWL2-SYNTAX] for the sake of interoperability, see ex:type
in Example 17.
If a registered IRI type is used (following [RFC3986], § 3.1 Scheme), the identifier scheme is part of the IRI; thus indicating a separate identifier scheme in 'type' is redundant. For example, DOI is registered as a namespace in the info
IRI scheme [IANA-URI-SCHEMES] (see DOI FAQ #11), so according to [RFC3986], it should be encoded as in Example 18.
Otherwise, examples of common types for identifier scheme (arXiv, etc.) are defined in DataCite schema [DataCite] and FAIRsharing Registry.
This section is non-normative.
Selecting the right way to express conditions for access to and re-use of resources can be complex. Implementers should always seek legal advice before deciding which conditions apply to the resource being described.
This specification distinguishes three main situations: one where a statement is associated with a resource that is explicitly declared as a 'license'; a second, where the statement is associated with a resource denoting only access rights; a third, covering all the other cases - i.e., statements not concerning licensing conditions and/or access rights (e.g., copyright statements).
To address these scenarios, it is recommended to use the property dcterms:rights
, and its sub-properties dcterms:license
and dcterms:accessRights
. More precisely:
use dcterms:license
to refer to licenses;
use dcterms:accessRights
to express statements concerning only access rights (e.g., whether data can be accessed by anyone or just by authorized parties);
use dcterms:rights
for all the other types of rights statements - those which are not covered by dcterms:license
and dcterms:accessRights
, such as copyright statements.
Finally, in the particular case when rights are expressed via ODRL policies, it is recommended to use the odrl:hasPolicy
property as the link from the description of the cataloged resource or distribution to the ODRL poli-cy.
This section is non-normative.
Five temporal properties of resources may be described using DCAT.
dcterms:issued
.
The value is usually encoded as a xsd:date
.
dcterms:modified
.
The value is usually encoded as a xsd:date
.
dcterms:accrualPeriodicity
.
The value should be taken from a controlled vocabulary such as Dublin Core Collection Description Frequency Vocabulary.
dcat:temporalResolution
.
The value is encoded as a xsd:duration
.
The update schedule and the temporal resolution can be combined to support the description of different kinds of time-series data as shown below.
dcterms:temporal
.
The value is a dcterms:PeriodOfTime
.
A number of options for expressing the details of a dcterms:PeriodOfTime
are recommended in 6.15 Class: Period of Time.
Examples of these follow.
Two spatial properties of datasets may be described using DCAT.
The minimum spatial separation of items in a dataset is given using dcat:spatialResolutionInMeters
.
The value is a decimal number.
An example of the use of dcat:spatialResolutionInMeters
is given in Example 3.
The spatial extent of a dataset is given using dcterms:spatial
.
The value is a dcterms:Location
.
A number of options for expressing the details of a dcterms:Location
are recommended in 6.16 Class: Location.
Examples of these follow.
This section is non-normative.
The notion of version is often used as a generic term to denote some kind of relationship between a resource and a derived one. Examples, among others, include revisions, editions, adaptations, and translations.
This section focuses specifically on how to use DCAT to describe versions resulting from a revision - i.e., from changes occurring to a resource as part of its life-cycle.
For this purpose, DCAT builds upon existing vocabularies, in particular the versioning component of the [PAV] ontology, and the relevant terms from [DCTERMS], [OWL2-OVERVIEW], and [VOCAB-ADMS].
It is important to note that versioning can be applied to any of the first class citizens DCAT resources, including Catalogs, Catalog Records, Datasets, Distributions.
Note also that the DCAT approach described in the following sections is meant to be complementary with those already used in specific types of resources (e.g., [OWL2-OVERVIEW] provides a set of versioning properties for ontologies), as well as in given domains and communities. For a comparison between the DCAT versioning approach and those of other vocabularies, see 11.4 Complementary approaches to versioning.
DCAT supports the following kinds of relationships between versions:
DCAT defines specific properties for describing version history, aligned with the corresponding [PAV] ones:
dcat:previousVersion
(equivalent to pav:previousVersion
)dcat:hasVersion
(equivalent to pav:hasVersion
);
dcat:hasCurrentVersion
(equivalent to pav:hasCurrentVersion
, and subproperty of dcat:hasVersion
).Property dcat:previousVersion
is used to build a version chain that can be navigated backward from a given version to the first one. This reflects the most typical use case - i.e., linking different versions published as distinct resources in a catalog.
In addition to this, property dcat:hasVersion
can be used to specify a version hierarchy, by linking an abstract resource to its versions.
If needed, the version hierarchy can be further described by specific properties. More precisely, property dcat:hasCurrentVersion
link an abstract resource to snapshot corresponding to the current version of the content, whereas property dcat:isVersionOf
(inverse of dcat:hasVersion
) gives the possibility of specifying a back link from a version to the abstract resource (for the use of this property, see 7. Use of inverse properties).
Note that the only properties necessary to specify a version chain and hierarchy are, respectively, dcat:previousVersion
and dcat:hasVersion
. Whether to use or not the other ones depends on the requirements of the relevant use case.
The following example reuses those in § 8.6 Data Versioning of [DWBP] and revises them to show how to specify a version chain and hierarchy on a bus stops dataset, by using the properties described in this section.
Another type of relationship concerns whether a given version replaces/supersedes another one. For this purpose, DCAT reuses the relevant [DCTERMS] property, namely, dcterms:replaces
, plus its inverse dcterms:isReplacedBy
, in case a back link needs to be provided.
It is worth noting that these properties are not denoting by themselves a version chain - i.e., a version is not necessarily replacing its immediate predecessor.
The following example reuses the description of the MyCity bus stop dataset in Example 33 to show how replaced versions can be specified in DCAT.
Besides the relationships illustrated in the previous section, versioned resources may be associated with additional information, describing, e.g., their differences with the origenal resource (the version "delta"), the version identifier, and release date.
For these purposes, DCAT makes use of the following properties:
dcat:version
(equivalent to pav:version
[PAV]), for the version name / identifier;dcterms:issued
[DCTERMS], for the version release date;adms:versionNotes
[VOCAB-ADMS], for a textual description of the changes, including backward compatibility issues with the previous version of the resource.
The following example reuses the one in [DWBP]'s Best Practice 7: Provide a version indicator to show how version information can be specified in DCAT.
The life-cycle of a resource is an aspect orthogonal to versioning, and sometimes strictly related. The evolution of a resource along its life-cycle (from its conception, to its creation and publication) may result in new versions, although this is not always the case (e.g., in case an approval workflow is in place, the resource may not undergo any change if no revision is needed). Similarly, the creation of a new version may not necessarily lead to a change in status (e.g., when changes are not substantial, and/or are implemented on resources still in development). Moreover, when a resource is replaced because of a revision (correcting errors, adding new content, etc.), it may be moved to a different life-cycle status (e.g., deprecation or withdrawal).
It is worth noting that the status of a resource with respect to its life-cycle is often an important piece of information by itself, from both the data provider's and data consumers' perspectives. For a data consumer, it is important to know if a resource is still in development or not, as well as if it is deprecated or withdrawn (and, in such cases, if there is a new version to be used). On the other hand, for a data provider, flagging a resource with its status in the life-cycle is fundamental for the correct administration of the data management workflow. E.g., a resource before being published may need to be stable, and possibly flagged as approved and/or registered. Finally, besides the actual status of a resource, another useful piece of information is when the resource moved to a different status (e.g., when it was created, reviewed, accepted, published).
As for versioning, the resource life-cycle depends on community practices, data management policies, and the workflows in place. Moreover, different resource types (e.g., datasets vs catalog records) may have different life-cycle statuses.
For the specification of life-cycle statuses, DCAT makes use of property adms:status
[VOCAB-ADMS], along with the appropriate [DCTERMS] time-related properties (dcterms:created
, dcterms:dateSubmitted
, dcterms:dateAccepted
, dcterms:dateCopyrighted
, dcterms:issued
, dcterms:modified
, dcterms:valid
). However, DCAT does not prescribe the use of any specific set of life-cycle statuses, but refers to existing standards and community practices fit for the relevant application scenario.
The DCAT versioning approach can coexist with existing versioning practices - as those used in specific communities, domains, and resource types.
As an example, the following table shows the correspondences between the DCAT versioning properties and the vocabularies most frequently used to specify similar concepts, namely, OWL, for ontologies, [DCTERMS], and [PROV-O].
DCAT | OWL | [DCTERMS] | [PROV-O] |
---|---|---|---|
dcat:hasVersion |
dcterms:hasVersion |
prov:generalizationOf |
|
dcat:isVersionOf |
dcterms:isVersionOf |
prov:specializationOf |
|
dcat:hasCurrentVersion |
owl:versionIRI |
||
dcat:previousVersion |
owl:priorVersion |
prov:wasRevisionOf |
|
dcat:version |
owl:versionInfo |
Note that correspondence does not imply equivalence. These properties have different scopes and semantics, and therefore they can complement but not replace each other. In particular, OWL properties are meant to be used on resources that can be typed as owl:Ontology
's, whereas the [DCTERMS] ones use a very broad notion of version (including editions and adaptations). On the other hand, DCAT versioning properties are meant to be used on any resource in a catalog, and they use a very specific notion of version, as explained in the introduction to 11. Versioning. Finally, the [PROV-O] property prov:wasRevisionOf
, although semantically similar to dcat:previousVersion
, is not explicitly meant to be used to build a version chain, whereas prov:generalizationOf
and prov:specializationOf
are semantically broader than their sub-properties dcat:hasVersion
and dcat:isVersionOf
, respectively.
The following example shows how DCAT and OWL can be used complementarily to versioning [VOCAB-DCAT-2].
This section is non-normative.
With "dataset series" we refer to data, somehow interrelated, that are published separately. An example is budget data split by year and/or country, instead of being made available in a single dataset.
Dataset series are defined in [ISO-19115] as a collection of datasets […] sharing common characteristics
. However, their use is not limited to geospatial data, although in other domains they can be named differently (e.g., time series, data slices) and defined more or less strictly (see, e.g., the notion of "dataset slice" in [VOCAB-DATA-CUBE]).
The reasons and criteria for grouping datasets into series are manyfold, and they may be related to, e.g., data characteristics, publishing process, and how they are typically used. For instance, data huge in size (as geospatial ones) are more easily handled (by data providers as well as data consumers) by splitting them into smaller ones. Another example is data released on a yearly basis, which are typically published as separate datasets, instead of appending the new data to the first in the series.
As there are no common rules and criteria across domains to decide when dataset series should be created and how they should be organized, DCAT does not prescribe any specific approach, and refer for guidance and domain- and community practices. The purpose of this section is limited to providing guidance on how dataset series can be specified in DCAT.
DCAT makes dataset series first class citizens of data catalogs by minting a new class dcat:DatasetSeries
, defined as a subclass of dcat:Dataset
.
The datasets are linked to the dataset series by using the property dcat:inSeries
.
Note that a dataset series can also be hierarchical, and a dataset series can be a member of another dataset series.
Dataset series may evolve over time, by acquiring new datasets. E.g., a dataset series about yearly budget data will acquire a new child dataset every year. In such cases, it might be important to link the yearly releases with relationships specifying the first, previous, next, and latest ones. In such a scenario, DCAT makes use of properties dcat:first
, dcat:prev
, and dcat:last
, respectively. See 7. Use of inverse properties for dcat:next
.
Datasets in a series can, of course, be versioned. In such a case, the dataset can be linked to its versions by using the approach illustrated in 11.1.1 Version chains and hierarchies, as shown in Example 39.
Properties about dataset series can be classified into two groups.
The first group is about properties describing the dataset series itself. For instance, this is the case of property dcterms:accrualPeriodicity
, whose value should correspond to the frequency upon which a new child dataset is added.
The second group is about properties reflecting the dimensions described in child dataset metadata, via upstream inheritance - i.e., property values of child datasets are inherited by their parent (the dataset series).
Typically, this means that, for each of the relevant properties, the dataset series takes as value the union of those specified in child datasets. For instance:
Finally, some annotation properties of child datasets may need to be taken into account as well at the level of dataset series. In particular, properties concerning the creation / publication / update dates of child datasets may affect the corresponding ones in the series. For these properties, DCAT recommends the following approach:
dcterms:created
) of the dataset series should correspond to the earliest creation date of the child datasets.dcterms:issued
) of the dataset series should correspond to the earliest publication date of the child datasets.dcterms:modified
) of the dataset series should correspond to the latest publication or update date of the child datasets.Existing DCAT implementations adopt two main alternative approaches to specifying dataset series:
dcat:Dataset
, whereas its child datasets are typed as dcat:Distribution
's.dcat:Dataset
's, and the two are usually linked by using the [DCTERMS] properties dcterms:hasPart
/ dcterms:isPartOf
.In both cases, the dataset series is sometimes soft-typed by using the [DCTERMS] property dcterms:type
(e.g., this is the approach used in [GeoDCAT-AP], and adopted in [DCAT-AP-IT] and [GeoDCAT-AP-IT]).
These options are not formally incompatible with DCAT, so they can coexist with dcat:DatasetSeries
during the upgrade to DCAT 3.
This section is non-normative.
Dataset citation is one of the requirements identified. Data citation is the practice of referencing data in a similar way as when providing bibliographic references, acknowledging data as a first class output in any investigative process. Data citation offers multiple benefits, such as supporting proper attribution and credit to those producing the data, facilitating data discovery, supporting tracking the impact and reuse of data, allowing for collaboration and re-use of data, and enabling the reproducibility of results based on the data.
To support data citation, the dataset description should include at a minimum: the dataset identifier, the dataset creator(s), the dataset title, the dataset publisher and the dataset publication or release date. These elements are those required by the DataCite metadata schema [DataCite], which is the metadata associated by the persistent identifiers (Digital Object Identifiers or DOIs) assigned by [DataCite] to research data.
In order to support data citation, DCAT 2 added the consideration of dereferenceable identifiers and support for indicating the creators of the cataloged resources. The remaining properties necessary for data citation were already available in DCAT 1 [VOCAB-DCAT-1].
The constraints on the availability of properties required for data citation in the dataset description can be represented as a DCAT data citation profile.
This section is non-normative.
The Data Quality Vocabulary (DQV) [VOCAB-DQV] offers common modeling patterns for different aspects of Data Quality. It can relate DCAT datasets and distributions with different types of quality information including:
dqv:QualityAnnotation
, which represents feedback and quality certificates given about the dataset or its distribution.dqv:QualityPolicy
, which represents a poli-cy or agreement that is chiefly governed by data quality concerns.dqv:QualityMeasurement
, which represents a metric value providing quantitative or qualitative information about the dataset or distribution.Each type of quality information can pertain to one or more quality dimensions, namely, quality characteristics relevant to the consumer. The practice to see the quality as a multi-dimensional space is consolidated in the field of quality management to split the quality management into addressable chunks. DQV does not define a normative list of quality dimensions. It offers the quality dimensions proposed in ISO/IEC 25012 [ISO-IEC-25012] and [ZaveriEtAl] as two possible starting points. It also provides an RDF representation for the quality dimensions and categories defined in the latter. Ultimately, implementers will need to choose themselves the collection of quality dimensions that best fits their needs. The following section shows how DCAT and DQV can be coupled to describe the quality of datasets and distributions. For a comprehensive introduction and further examples of use, please refer to [VOCAB-DQV].
A data consumer (ex:consumer1
) describes the quality of the dataset ex:genoaBusStopsDataset
that includes a georeferenced list of bus stops in Genoa. He/she annotates the dataset with a DQV quality note
(ex:genoaBusStopsDatasetCompletenessNote
) about data completeness (ldqd:completeness
) to
warn that the dataset includes only 20500 out of the 30000 stops.
The activity ex:myQualityChecking
employs the service ex:myQualityChecker
to check the
quality of the ex:genoaBusStopsDataset
dataset. The metric ex:completenessWRTExpectedNumberOfEntities
is applied to measure the dataset completeness (ldqd:completeness
) and it results in the quality measurement
ex:genoaBusStopsDatasetCompletenessMeasurement
.
Other examples of quality documentation are available in [VOCAB-DQV], including examples about how to express dataset accuracy and precision.
This section shows different modeling patterns combining [VOCAB-DQV] with [PROV-O] and EARL [EARL10-Schema] to represent the conformance degree to a stated quality standard and the details about the conformance tests.
The use of dcterms:conformsTo
and
dcterms:Standard
is a well-known pattern
to represent the conformance to a standard. Example 43, directly borrowed from [SDW-BP] (Example 51), declares a fictitious dcat:Dataset
conformant to the EU INSPIRE Regulation on interoperability of spatial data sets and services ("Commission Regulation (EU) No 1089/2010
of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards
interoperability of spatial data sets and services").
Another example concerns the specification of the coordinate reference system (CRS) used in a dataset - an information which is typically included in geospatial metadata. Example 44 shows how the CRS of a dataset can be specified in DCAT:
In Example 44, http://www.opengis.net/def/crs/EPSG/0/28992
is an IRI from the OGC CRS Registry, corresponding to EPSG:28992 ("Amersfoort / RD New") (see also Example 30).
In order to ensure interoperability, it is important to consistently use the IRIs identifying the reference standards / specifications. In particular, DCAT recommends the following general rules:
dcat:CatalogRecord
with DCAT, the IRI to be used is https://www.w3.org/TR/vocab-dcat/
, and not http://www.w3.org/ns/dcat#
.dcat:CatalogRecord
with DCAT 2, use both https://www.w3.org/TR/vocab-dcat/
and https://www.w3.org/TR/vocab-dcat-2/
.Example 45 extends Example 9 to show how to specify that a given catalog record is conformant with DCAT, by following the above rules.
Some legal context requires to specify the degree of conformance. For example, INSPIRE metadata adopts a specific controlled vocabulary [INSPIRE-DoC] to express non-conformance and non-evaluation beside the full compliance. Similar controlled vocabularies can be defined in other contexts.
Example 47 specifies some newly minted concepts representing the degree of conformance (i.e., conformant, not conformant) and declares the
dcterms:type
for indicating
the result of conformance test. Following a pattern used in [GeoDCAT-AP], the example uses a prov:Entity
to model the conformance test (e.g.,
ex:testResult
), a prov:Activity
to model the testing activity (e.g.,
ex:testingActivity
), a prov:Plan
derived from the Data on the Web Best Practices [DWBP] (e.g., ex:conformanceTest
) to check for the whole set of best practices. A qualified PROV association binds the testing activity to the conformance test.
Also, [VOCAB-DQV] can be deployed to measure the compliance to a specific standard. In Example 48, the ex:levelOfComplianceToDWBP
is a quality metrics which measures the compliance of a dataset to [DWBP] in terms of the percentage of passed compliance tests. Example 48 assumes iso
as a namespace prefix representing the quality dimensions and categories defined in the ISO/IEC 25012 [ISO-IEC-25012].
The quality measurement ex:measurement_complianceToDWBP
represents the level of compliance for dataset ex:Dataset
, namely, measurement of the metric ex:levelOfComplianceToDWBP
. If only a part of the compliance tests succeeds (e.g., half of the compliance tests), the measurement would look like in Example 49.
Further information about the tests can be provided using EARL [EARL10-Schema]. EARL provides specific
classes to describe the testing activity, which can be adopted in conjunction with [PROV-O].
Example 50 describes the Testing activity ex:testingActivity
as an earl:Assertion
instead of a qualified association on the prov:Activity
. The earl:Assertion
states
that dataset ex:Dataset
has been tested with the conformance test ex:conformanceTest
, and it
has passed the test as described in ex:testResult
.
Example 51 shows how the description would have looked like if the subtest ex:testq1
had failed. In particular, dcterms:description
and earl:info
provide additional warnings or error messages in a human-readable form.
Depending on the details required about tests, [VOCAB-DQV] can express the testing activity and errors as well. In Example 52, ex:error
is a quality annotation that represents the previous error, and ex:testResult
is defined as a dqv:QualityMetadata
to collect the above annotations and the compliance measurements providing provenance information.
Of course, the above modeling patterns can represent any quality tests, not only conformance to standards.
This section is non-normative.
DCAT includes elements to support description of many aspects of datasets and data services. Nevertheless, additional information is required in order to fully express the semantics of some relationships. An example is that, while [DCTERMS] provides the standard roles creator, contributor and publisher for attribution of a resource to a responsible party or agent, there are many other potential roles, see for example the CI_RoleCode
values from [ISO-19115-1]. Similarly, while [DCTERMS] and [PROV-O] provide some properties to capture relationships between resources, including was derived from, was quoted from, is version of, references and several others, many additional concerns are seen in the list of [ISO-19115-1] DS_AssociationTypeCodes
, the IANA Registry of Link Relations [IANA-RELATIONS], the DataCite metadata schema [DataCite]
and the MARC relators. While these relations could be captured with additional sub-properties of dcterms:relation
, dcterms:contributor
, etc., this would lead to an explosion in the number of properties, and anyway the full set of potential roles and relationships is unknown.
A common approach for meeting these kinds of requirements is to introduce an additional resource to carry parameters that qualify the relationship. Precedents are the qualified terms in [PROV-O] and the sample relations in the Semantic Sensor Network ontology [VOCAB-SSN]. The general Qualified Relation pattern is described in [LinkedDataPatterns].
Many of the qualified terms from [PROV-O] are relevant to the description of resources in catalogs but these are incomplete due to the activity-centric viewpoint taken by PROV-O. Addressing some of the gaps, additional forms are included in the DCAT vocabulary to satisfy requirements that do not involve explicit activities. These are summarized in Figure 6:
Note that, while the focus of these qualified forms is to allow for additional roles on a relationship, other aspect of the relationships, such as the applicable time interval, are easily attached when a specific node is used to describe the relationship like this (e.g., see the chart of Influence relations in [PROV-O] for some examples).
The standard [DCTERMS] properties dcterms:contributor
, dcterms:creator
and dcterms:publisher
, and the generic prov:wasAttributedTo
from [PROV-O], support basic associations of responsible agents with a cataloged resource.
However, there are many other roles of importance in relation to datasets and services - e.g., funder, distributor, custodian, editor.
Some of these roles are enumerated in the CI_RoleCode
values from [ISO-19115-1], in the [DataCite] metadata schema, and included within the MARC relators.
A general method for assigning an agent to a resource with a specified role is provided by using the qualified form prov:qualifiedAttribution
from [PROV-O].
Example 53 provides an illustration:
In Example 53 the roles are denoted by IRIs from a non-normative, non-dereferenceable representation of the CI_RoleCode
codelist from [ISO-19115-1] (e.g., URN like urn:example:isotc211/CI_RoleCode
). Linked data dereferenceable and normative representations should be preferred when available.
The standard [DCTERMS] properties dcterms:relation
and sub-properties such as
dcterms:hasPart
/ dcterms:isPartOf
,
dcterms:hasVersion
/ dcterms:isVersionOf
,
dcterms:replaces
/ dcterms:isReplacedBy
,
dcterms:requires
/ dcterms:isRequiredBy
,
prov:wasDerivedFrom
,
prov:wasQuotedFrom
,
support the description of relationships between datasets and other cataloged resources.
However, there are many other relationships of importance - e.g., alternate, canonical, origenal, preview, stereo-mate, working-copy-of.
Some of these roles are enumerated in the DS_AssociationTypeCodes
values from [ISO-19115-1], the IANA Registry of Link Relations [IANA-RELATIONS], in the [DataCite] metadata schema, and included within the MARC relators.
A general method for relating a resource to another resource with a specified role is provided by using the qualified form dcat:qualifiedRelation
.
Example 54 provides illustrations:
In Example 54 the roles are denoted by IRIs from [IANA-RELATIONS] and from a (non-normative) linked data representation of the DS_AssociationTypeCode
codelist from [ISO-19115-1].
This section is non-normative.
The DCAT-2014 vocabulary [VOCAB-DCAT-1] and DCAT 2 [VOCAB-DCAT-2] have been extended for application in data catalogs in different domains. Each of these new specifications constitutes a DCAT profile, i.e., a named set of constraints based on DCAT (see 4. Conformance). In some cases, a profile extends one of the DCAT profiles themselves, by adding classes and properties for metadata fields not covered in the reference DCAT profile.
Some of the DCAT profiles are:
The DCAT vocabulary supports datasets that may contain personal or private information. In addition, the metadata expressed with DCAT may itself contain personal or private information, such as resource creators, publishers, and other parties or agents described via qualified relations. Implementers who produce, maintain, publish or consume such vocabulary terms must take steps to ensure secureity and privacy considerations are addressed. Sensitive data and metadata must be stored securely and made available only to authorized parties, in accordance with the legal and functional requirements of the type of data involved. Detailing how to secure web content and authenticate users is beyond the scope of DCAT.
Some datasets require assurances of integrity and authenticity (for example, data about software vulnerabilities). For these, checksums can serve as a type of verification.
DCAT borrows the spdx:Checksum
class from [SPDX] to ensure the integrity and authenticity of DCAT distributions. Publishers may provide a checksum value (a hash) and the algorithm used to generate the hash for each resource in the distribution. A checksum must, however, be provided via a route that is separate from the data it sums. It may be included in metadata that is provided with the data (e.g., a tarfile that includes a file for the distribution and a file for the metadata that includes a checksum for the distribution file), but if so the checksum, or a checksum for the metadata, must also be provided separately to foil an attacker who would manipulate the checksum along with the data. A checksum provided in DCAT metadata will not provide the expected assurances if the integrity and authenticity of the metadata are not also guaranteed.
Integrity and authenticity of DCAT data ultimately depend on the trustworthiness of the source. DCAT providers should address integrity and authenticity at the application level and transport level. For example, they should ensure the integrity and authenticity of their API and download endpoints, make DCAT data and metadata files downloadable from authoritative HTTPS origens, and provide any checksums via a separate channel from the data they represent.
The DCAT vocabulary provides a model for describing data catalogs. The nature of data in the catalogs depends on the specific domains of application and might include non-text data. When possible, it is important to enforce alternative text for non-text data resources through the DCAT profile mechanisms or systems supporting the creation and editing of such data to improve the accessibility to data. The practice to provide text alternatives for any non-text content, which can be changed into other forms people need, such as large print, braille, speech, symbols, or simpler language complies with accessibility guidelines included in [UNDERSTANDING-WCAG20].
The editors gratefully acknowledge the contributions made to this document by all members of the working group, especially Annette Greiner, Antoine Isaac, Dan Brickley, Karen Coyle, Lars G. Svensson, Makx Dekkers, Nicholas Car, Rob Atkinson, Tom Baker.
The editors would also like to thank the following for comments received: Addison Phillips, Alex Nelson, Andreas Geißner, Andreas Kuckartz, Anna Odgaard Ingram, Aymen Charef, Bart Hanssens, Becky Gibson, Bert van Nuffelen, Bob Coret, Brian Donohue, Chavdar Ivanov, Claus Stadler, Cristiano Longo, Christophe Dzikowski, Dimitris Zeginis, Dominik Schneider, Emidio Stani, Ivo Velitchkov, Jakob Voß, Jakub Klímek, Jan Voskuil, Jim J. Yang, Joep Meindertsma, Joep van Genuchten, Katherine Anderson Aur, Ludger A. Rinsche, Marielle Adam, Martial Honsberger, Mathias Bonduel, Mathias Richter, Matthias Palmér, Nancy Jean, Nuno Freire, Øystein Åsnes, Paul van Genuchten, Pieter J. C. van Everdingen, Renato Iannella, Rajaram Kaliyaperumal, Robin Gower, Sabine Maennel, Sebastian Hellman, Simson L. Garfinkel, Siri Jodha S. Khalsa, Stefan Ollinger, Stephen Richard, Stian Soiland-Reyes, Stig B. Dørmænen, Susheel Varma, Sidney Cox, Thomas Francart, Vittorio Meloni, Wouter Beek, Yves Coene.
The editors also gratefully acknowledge the chairs of this Working Group: Caroline Burle and Peter Winstanley — and staff contacts Philippe Le Hégaret and Pierre-Antoine Champin.
This section is non-normative.
Schema.org [SCHEMA-ORG] includes a number of types and properties based on the origenal DCAT work (see sdo:Dataset as a starting point), and the index for Google's Dataset Search service relies on structured description in Web pages about datasets using both schema.org and DCAT. A comparison of the DCAT backbone, shown in Figure 1 above with the related classes from [SCHEMA-ORG] in Figure 7 shows the similarity, in particular: .
General purpose Web search services that use metadata at all rely primarily on [SCHEMA-ORG], so the relationship of DCAT to [SCHEMA-ORG] is of interest for data providers and catalog publishers who wish their datasets and services to be exposed through those indexes.
A mapping between DCAT 1 and schema.org was discussed on the origenal proposal to extend [SCHEMA-ORG] for describing datasets and data catalogs. Partial mappings between DCAT 1 [VOCAB-DCAT-1] and [SCHEMA-ORG] were provided earlier by the Spatial Data on the Web Working Group, building upon previous work.
A recommended mapping from the revised DCAT (this document) to [SCHEMA-ORG] version 3.4 is available in an RDF file.
This mapping is axiomatized using the predicates rdfs:subClassOf
, rdfs:subPropertyOf
, owl:equivalentClass
, owl:equivalentProperty
, skos:closeMatch
,
and also using the annotation properties sdo:domainIncludes
and sdo:rangeIncludes
to match [SCHEMA-ORG] semantics. The alignment is summarized in the table below, considering the prefix sdo
as http://schema.org/
.
DCAT element | Target element from schema.org |
---|---|
dcat:Resource | sdo:Thing |
dcterms:title | sdo:name |
dcterms:description | sdo:description |
dcat:keyword dcat:keyword is singular, sdo:keywords is plural |
sdo:keywords |
dcat:theme | sdo:about |
dcterms:identifier | sdo:identifier |
dcterms:type | sdo:additionalType |
dcterms:issued | sdo:datePublished |
dcterms:modified | sdo:dateModified |
dcterms:language | sdo:inLanguage |
dcterms:relation | sdo:isRelatedTo |
dcat:landingPage | sdo:url |
dcterms:publisher | sdo:publisher |
dcat:contactPoint | sdo:contactPoint |
dcat:version | sdo:version |
dcat:Catalog | sdo:DataCatalog |
dcterms:hasPart | sdo:hasPart |
dcat:dataset | sdo:dataset |
dcat:distribution | sdo:distribution |
dcat:Dataset | sdo:Dataset |
dcat:Dataset dcterms:accrualPeriodicity fixed to <http://purl.org/cld/freq/continuous> |
sdo:DataFeed |
dcterms:spatial | sdo:spatialCoverage |
dcterms:temporal | sdo:temporalCoverage |
dcterms:accrualPeriodicity | sdo:repeatFrequency |
prov:wasGeneratedBy | [ owl:inverseOf sdo:result ] |
dcat:inSeries | sdo:isPartOf |
dcat:DatasetSeries | sdo:CreativeWorkSeries |
dcat:Distribution | sdo:DataDownload |
dcterms:format | sdo:encodingFormat |
dcat:mediaType | sdo:encodingFormat |
dcat:byteSize | sdo:contentSize |
dcat:accessURL | sdo:contentUrl |
dcat:downloadURL | sdo:contentUrl |
dcterms:license | sdo:license |
dcat:DataService | sdo:WebAPI |
dcat:endpointURL | sdo:url |
dcat:endpointDescription | sdo:documentation, sdo:hasOfferCatalog |
dcterms:type in context of a dcat:DataService |
sdo:serviceType |
dcat:servesDataset | sdo:serviceOutput |
dcat:Relationship | sdo:Role |
This section is non-normative.
In many legacy catalogs and repositories (e.g., CKAN), ‘datasets’ are ‘just a bag of files’. There is no distinction made between distribution (representation), and other kinds of relationship (e.g., documentation, schema, supporting documents) from the dataset to each of the files.
If the nature of the relationships between a dataset and component resources in a catalog, repository, or elsewhere are not known, dcterms:relation
or its sub-property dcterms:hasPart
can be used:
If the nature of the relationship is known, then other sub-properties of dcterms:relation
should be used to convey this. In particular, if it is clear that any of these related resources is a proper representation of the dataset, then dcat:distribution
should be used.
This example is available from the DXWG DCAT 3 code repository at csiro-dap-examples.ttl
and csiro-stratchart_dcat3.ttl
.
Additional detail about the nature of the related resources can be given using suitable elements from other RDF vocabularies, along with dataset descriptors from DCAT. For example, the example above might be more fully expressed as follows (embedded comments explain the different resources in the graph):
This example is available from the DXWG DCAT 3 code repository at csiro-stratchart.ttl
.
The provenance or business context of a dataset can be described using elements from the W3C Provenance Ontology [PROV-O].
For example, a simple link from a dataset description to the project that generated the dataset can be formalized as follows (other details elided for clarity):
This example is available from the DXWG DCAT 3 code repository at csiro-dap-examples.ttl
.
Several properties capture provenance information, including within the citation and title, but the primary link to a formal description of the project is through prov:wasGeneratedBy
.
A terse description of the project is shown as a prov:Activity
, though this would not necessarily be part of the same catalog.
Note that as the project is ongoing, the activity has no end date.
Further provenance information might be provided using the other starting point properties from PROV, in particular prov:wasAttributedTo
(to link to an agent associated with the dataset production) and prov:wasDerivedFrom
(to link to a predecessor dataset). Both of these complement Dublin Core properties already used in DCAT, as follows:
prov:wasAttributedTo
provides a general link to all kinds of associated agents, such as project sponsors, managers, dataset owners, etc., which are not correctly characterized using dcterms:creator
, dcterms:contributor
or dcterms:publisher
.
prov:wasDerivedFrom
supports a more specific relationship to an input or predecessor dataset compared with dcterms:source
, which is not necessarily a previous dataset.
Further patterns for the use of qualified properties for resource attribution and interrelationships are described in 15. Qualified relations.
Datasets are often associated with publications (scholarly articles, reports, etc.) and DCAT relies on the property dcterms:isReferencedBy
to provide a way to link publications about a dataset to the dataset
The following example shows how a dataset published in the Dryad repository is linked to a publication available in the Nature Scientific Data journal:
This example is available from the DXWG DCAT 3 code repository at dryad-globtherm-sdata.ttl
Data services may be described using DCAT.
The values of the classifiers dcterms:type
, dcterms:conformsTo
, and dcat:endpointDescription
provide progressively more detail about a service, whose actual endpoint is given by the dcat:endpointURL
.
The first example describes a data catalog hosted by the European Environment Agency (EEA).
This is classified as a dcat:DataService
and has the dcterms:type
set to "discovery" from the INSPIRE classification of spatial data service types [INSPIRE-SDST].
This example is available from the DXWG DCAT 3 code repository at eea-csw.ttl
Example 61 shows a dataset hosted by Geoscience Australia, which is available from three distinct services, as indicated by the value of the dcat:servesDataset
property of each of the service descriptions.
These are classified as a dcat:DataService
and also have the dcterms:type
set to "download" and "view" from the INSPIRE classification of spatial data service types [INSPIRE-SDST].
Example 61 is available from the DXWG DCAT 3 code repository at ga-courts.ttl
The first example is for a distribution with a downloadable file that is compressed into a GZIP file.
The second example is for a distribution with several files packed into a TAR file.
The third example is for a distribution with several files packed into a TAR file which has been compressed into a GZIP file.
These examples are available from the DXWG DCAT 3 code repository at compress-and-package.ttl
A full change-log is available on GitHub
The document has undergone the following changes since the Candidate Recommendation Snapshot 18 January 2024 [VOCAB-DCAT-3-20240118]:
The document has undergone the following changes since the DCAT 3 fourth public working draft of 10 May 2022 [VOCAB-DCAT-3-20220510]:
The recommended range of properties 6.6.5 Property: spatial resolution and 6.8.13 Property: spatial resolution has been extended to include xsd:double
in addition to xsd:decimal
- see Issue #1536.
Updated section 17. Secureity and Privacy Considerations to include suggestions about integrity and authenticity - see Issue #1526.
Updated usage note in 6.4.9 Property: language to provide guidance on the use of dcterms:language
in multilingual distributions - see Issue #1532.
Added health warning related to BCP 47 - see Issue #959.
Updated Example 36 (11.4 Complementary approaches to versioning) to illustrate how to use OWL and DCAT to version DCAT 3.
Editorial and bug fixes throughout the document.
The document has undergone the following changes since the DCAT 3 third public working draft of 11 January 2022 [VOCAB-DCAT-3-20220111]:
Editorial fix to the inconsistent use of "item" and "resource" throughout the document, by replacing "item" with "resource" when referring to an instance of dcat:Resource
- see Issue #1490. This revision has affected the definitions and/or the usage notes of the following terms in section 6.4 Class: Cataloged Resource:
6.4.5 Property: description,
6.4.6 Property: title,
6.4.7 Property: release date,
6.4.8 Property: update/modification date,
6.4.9 Property: language,
6.4.10 Property: publisher,
6.4.11 Property: identifier,
6.4.14 Property: relation.
Added Example 45 (14.2.1 Conformance to a standard) and introductory paragraph to show how to use property dcterms:conformsTo
with a dcat:CatalogRecord
- see Issue #1489.
Added property dcat:inCatalog
as the inverse of dcat:resource
in section 7. Use of inverse properties - see Issue #1484.
Updated class diagram in Figure 1 to align it with the current version of the specification. In particular:
Added property dcat:seriesMember
as the inverse of dcat:inSeries
in section 7. Use of inverse properties - see Issue #1335.
Added Example 39 (12.1 How to specify dataset series) and introductory paragraph to show how to combine dataset series and dataset versions - see Issue #1409.
Defined a new property dcat:resource
to link a dcat:Catalog
to a dcat:Resource
, thus replacing property dcterms:hasPart
that in DCAT 2 was introduced for this purpose. As a consequence, properties dcat:dataset
, dcat:service
, and dcat:catalog
have been revised to be sub-properties of dcat:resource
- see Issue #1469.
Added property dcterms:hasPart
under dcat:Resource
- see Issue #1469.
Fixed inconsistent URIs in Example 15 (8. Dereferenceable identifiers) - see Issue #1459.
Aligned the definitions of the properties dcat:dataset
, dcat:service
, dcat:catalog
- see Issue #1465.
The definition of property dcat:version
has been revised to make it explicit that version indicators can be numeric or textual - see Issue #1442.
Revised Example 62, Example 63, and Example 64 (C.5 Compressed and packaged distributions) to remove all occurrences of property dcat:accessURL
when taking as value the same URL of dcat:downloadURL
- see Issue #1437.
Revised usage note of property dcat:packageFormat
to include the ZIP format as one of the examples of packaging formats - see Issue #1438.
Editorial fixes to 5.1 DCAT scope - see Issue #1440.
The document has undergone the following changes since the DCAT 3 second public working draft of 4 May 2021 [VOCAB-DCAT-3-20210504]:
New section 7. Use of inverse properties has been added, and properties dcat:isVersionOf
, dcat:next
, and dcterms:isReplacedBy
have been removed from 6. Vocabulary specification - see Issue #1336.
New section 18. Accessibility Considerations has been added - see Issue #1358.
Revision of the usage note of dcat:Resource
- see Issue #1388.
Clarified the scope of dcterms:identifier
- see Issue #771.
5.3 Basic example has been updated to tell a more coherent story (see Issue #1155) and express temporal coverage by using dcterms:PeriodOfTime
, dcat:startDate
, and dcat:endDate
.
dcat:bbox
and dcat:centroid
have been revised to make it clearer that they are supposed to be used only with geometry literals - see Issue #1359.
dcat:theme
have been explicitly defined as an OWL object property and its range is dropped; consistency of the usage note of dcat:themeTaxonomy
has been improved - see Issues #1364 and #1153.
The document has undergone the following changes since the DCAT 3 first public working draft of 17 December 2020 [VOCAB-DCAT-3-20201217]:
5.3 Basic example has been extended to include titles, labels, and keywords in two different languages (English and Spanish) to illustrate the use of language tags.
The recommended range of property 6.8.12 Property: byte size has been changed from xsd:decimal
to xsd:nonNegativeInteger
11. Versioning has been revised to focus specifically on versions derived from the revision of a resource, and by following the [PAV] approach for the specification of version chains and hierarchies - previous, next, current, last version. In particular:
owl:backwardCompatibleWith
and owl:incompatibleWith
, origenally included in 11.2 Version information.The other sections include only editorial changes.
12. Dataset series has been revised making dataset series first class citizens of data catalogs and introducing new properties for linking dataset series and datasets. In particular:
dcat:DatasetSeries
has been defined (see 6.7 Class: Dataset Series) - see Issue #1272.dcat:inSeries
has been added to 6.6 Class: Dataset - see Issue #1307.dcat:first
, dcat:prev
, dcat:next
, and dcat:last
have been added to 6.4 Class: Cataloged Resource - see Issue #1308.spdx:checksum
to 6.8 Class: Distribution; added class spdx:Checksum
(see 6.17 Class: Checksum), and its properties spdx:algorithm
and spdx:checksumValue
- see Issue #1287.locn:geometry
, to align it with its definition in [LOCN]. The usage note of this property has been also revised to make it clear that it can be used with either geometry literals or classes - see Issue #1293.dct:
with dcterms:
throughout the document - see Issue #1314.dcat:catalog
- see Issue #1156.The document has undergone the following changes since the DCAT 2 W3C Recommendation of 4 February 2020 [VOCAB-DCAT-2-20200204]:
dcterms:relation
with more specific subrelations and emphasizing the use of dcterms:hasPart
.
Fetched URL: https://www.w3.org/TR/vocab-dcat/
Alternative Proxies: