"The CLARIN Concept Registry (CCR) forms the basis of the semantic interopability layer of CLARIN, especially in the context of metadata, i.e., the Component MetaData Infrastructure (CMDI). It does so by offering a collection of concepts, identifiable by their persistent identifiers, relevant for the domain of language resources. (.) The Concept Registry can be accessed by anyone using a read-only facetted browser or via the search facilities of the CMDI Component Registry. Adding new concepts or changing existing ones can only be done by the national CCR coordinators. (...) In the past the concept registry role was taken by ISOcat, which was the ISO TC37 Data Category Registry (DCR) created in 2008 as one of the first ISO standards delivered in the form of a database (ISOcat). The Max Planck Institute for Psycholinguistics (MPI) has provided development, hosting, and support services and acted as the Registration Authority (RA). The use of the DCR by various communities, including CLARIN, has grown over the years. Feedback from users, coupled with changes in ISO standardization procedures, necessitated a review of the system and operational framework with an aim towards improving usability (see this LREC paper and this TKE paper).<br />
In line with these insights and MPI's renewed focus on institute research, the MPI stopped being the RA and hosting provider in December 2014. For CLARIN users the Meertens Institute hosts the new CLARIN Concept Registry (CCR). This registry contains the relevant concepts (based on the corresponding ISOcat data categories), such as those used by CMDI. The CCR has a less complex data model than ISOcat, and is also a closed registry, i.e., only the national CCR-coordinators are able to input and edit (new) concepts."