Import and Export Trade statistics are a rare example of real and genuine international co-operation. Virtually all the countries of the world use a common system of product classification, which is the six-digit Harmonised System (HS), agreed by the World Customs Organisation (WCO). The system starts at a 2 digit chapter breakdown consisting of 97 broad product sectors. Each of these sectors are further subdivided into 4 and 6 digit classifications. The 6 digit Harmonised System covers over 6,000 product headings. Individual countries can add extra digits to provide greater product detail, up to a total of 10 digits. For example in the EU the eight digit Combined Nomenclature classification subdivides the 6 digit HS:

The trade figures are collected by Customs Authorities at the point of entry/exit except for Intra-EU trade which is collected by direct enquiry from manufacturers and traders.