In order to present data sets in a well organised manner and to be able to search for data sets in a targeted manner, data sets on data.overheid.nl are described with metadata. The W3C has developed DCAT for this, a metadata standard for the description of data sets. Read more about DCAT by W3C.
DCAT standard European Union
The European Union has drawn up a DCAT application profile. The Dutch DCAT application profile is based on version 1.1 of the EU profile (more about DCAT-AP-EU 1.1 of the EU). An update of the DCAT-AP-EU is continuously underway. This includes mapping to ISO 19115, the metadata standard for geo data sets, among other things. Follow the developments of DCAT-AP-EU.
DCAT standard for the Dutch government: DCAT-DONL
The Dutch government has translated the DCAT-AP-EU into a Dutch application profile. The application profile for data sets is the specification of the metadata that the Dutch government uses for the exchange of metadata about datas ets between data catalogs. Data.overheid.nl is set up on the basis of DCAT-DONL. The application profile consists of a description of the data model, the value lists that are used to fill in the model and the way of exchanging information about data sets. The Dutch government has more application profiles (also called IPMs) for the exchange of other types of government information.
A new version of the data portal went live at the beginning of 2015, based on a new version of CKAN. The new portal is built according to DCAT-DONL. Full compatibility with the European DCAT standard has been achieved for Dutch data sets. A mapping has also been made to ISO 19115, the metadata standard for geo data sets used by the National GeoRegister (NGR). This allows us to raise the quality of the metadata exchange with other data catalogs in the Netherlands and Europe to a higher level.
Why DCAT for data sets?
Why use a Dutch application profile of DCAT? The application profile for data sets describes which information we exchange between Dutch data catalogs and which referential data we use for this. Because we limit ourselves to Dutch data catalogs, we can make agreements about the referential data to be used, such as identification of organisations, subject and theme classification. Some of these referential data are available as value lists (see DCAT-AP-DONL value lists) and are based on the standard OWMS value lists.
DCAT-DONL is intended to keep the exchange of metadata within the Netherlands simple. If Dutch Data Catalogs supply their metadata according to the application profile to data.overheid.nl, data.overheid.nl can then pass it on to the European data portal. In 2017 the documentation of a new version of DCAT was started, based on the new version DCAT-AP-EU 1.1. This has resulted in a documented DCAT standard DCAT-AP-DONL 1.1 (documentation: DCAT-AP-DONL 1.1).
Data.overheid.nl has drawn up the government profile for DCAT in collaboration with various parties. Its formal name is DCAT-AP-DONL 1.1. This version of DCAT is currently used on data.overheid.nl for the supply of data set metadata by other governments and external suppliers. Data.overheid.nl then delivers to the European data portal in DCAT format.
For all documentation and information about the special government profile for the exchange of metadata, please refer to the following page: