Is used as dct:language of dcat:Catalog, dcat:Dataset and dcat:Distribution.
No Controlled vocabulary on dcat-ap.de available
What we learned:
- DCAT-AP.de http://www.dcat-ap.de/def/dcatde/1_0/implRules.pdf states
Diese Eigenschaft bezieht sich auf die Sprache, welche in der textuellen Beschreibung der Metadaten der dem Katalog zugehörigen Datenstrukturen Verwendung findet (z.B. Titel, Beschreibungen usw.). Diese Eigenschaft kann wiederholt werden, falls die Metadaten in verschiedenen Sprachen zur Verfügung stehen.
Our position:
- The definition of dct:language http://udfr.org/docs/onto/dct_language.html states:
Recommended best practice is to use a controlled vocabulary such as RFC 4646.
- The definition of dct:LinguisticSystem:
Examples include written, spoken, sign, and computer languages.
We have the strong feeling that dct:LinguisticSystem is not the correct class to implement dct:Language. Dct:LinguisticSystem describes in which ways (Knots, bits, spoken words, noises) language is expressed and transportet. But dct:Language is in the interpretation of DCAT-AP.de simply the set of languages in which the metadata e.g. Title/Description is stored.
How to proceed:
If we follow the interpretation of DCAT-AP.de and simply interpret dct:Language as a Language (en, de, it etc.) then a second question arises about the controlled vocabulary to use.
The DCAT-AP Implementation guide states https://lists.w3.org/Archives/Public/public-dwbp-wg/2015Jul/att-0010/DCAT-APimplementationguide.pdf
dct :LinguisticSystem Here it is recommended to use 2 or 3 character codes provided in ISO 3166 https://www.iso.org/iso-3166-country-codes.html
Govdata.de uses http://publications.europa.eu/resource/authority/language in alpha-3 (3 letter) notation. The SKOS file can be found here http://publications.europa.eu/mdr/resource/authority/language/skos/languages-skos.rdf .
But be warned. The SKOS file is in a mixture of alpha-2 and alpha-3 notation:
<skos:Concept rdf:about="http://publications.europa.eu/resource/authority/language/ENG">
<skos:inScheme rdf:resource="http://publications.europa.eu/resource/authority/language"/>
at:authority-codeENG</at:authority-code>
at:op-codeENG</at:op-code>
atold:op-codeENG</atold:op-code>
dc:identifierENG</dc:identifier>
<skos:prefLabel xml:lang="bg">английски</skos:prefLabel>
<skos:prefLabel xml:lang="cs">angličtina</skos:prefLabel>
<skos:prefLabel xml:lang="da">engelsk</skos:prefLabel>
<skos:prefLabel xml:lang="de">Englisch</skos:prefLabel>
<skos:prefLabel xml:lang="el">αγγλικά</skos:prefLabel>
Please notice the xml:lang alpha-2 notation for the definition of an alpha-3 concept.