The following schema illustrates how various international, European and national classifications relevant to trade statistics relate to each other.  Each arrow indicates a relationship between a reference classification and a derived classification (to which it points).  Solid arrows indicate classifications linked by structure.  Dotted arrows and lines indicate classifications linked through conversion tables.

 Abbreviations:

ISIC: International Standard Industrial Classification of all Economic Activities
NACE: Statistical Classification of Economic Activities in the European Community
CPC: Central Product Classification
CPA: Classification of Products by Activity
HS: Harmonized Commodity Description and Coding System
CN: Combined Nomenclature
SITC: Standard International Trade Classification
PRODCOM: Classification of goods used for collection and dissemination of statistics on industrial production in the European Union.