The 33 national members of CEN (Comité Européen de Normalisation – Europäisches Komitee für Normung) are the National Standards Bodies (NSBs) of the 27 European Union countries plus Croatia, The Former Yugoslav Republic of Macedonia and Turkey plus three countries of the European Free Trade Association (Iceland, Norway and Switzerland).

Together with CENELEC (Comité Européen de Normalisation Electrotechnique - European Committee for Electrotechnical Standardization) CEN was assigned by the European Commission to develop standards which serve as a means for the attestation of conformity of products with the essential requirements of the relevant European directives. However, in the special case of the Construction Products Directive, these harmonized standards are not only a possible means, but after a transition period they are to be applied bindingly.