Imported and exported goods must be declared under specific subheadings or subdivisions of the Combined Nomenclature or of other nomenclatures they fall under, via the Classification Information System (CLASS). This determines the rate of customs duty of the Common Customs Tariff, or which non-tariff measures apply. The easy-to-use eLearning course CLASS System is based on the Union Customs Code and is produced by the European Commission Directorate General for Taxation and Customs (TAXUD) under the Customs Programme.