The HS forms the basis by which goods are classified and trade statistics are developed. National Customs authorities use this to compile their tariffs. The HS covers goods that have a physical dimension, and therefore it does not cover services.
There are 21 major sections with each section divided into 99 chapters. These chapters have more than 1200 main 4-digit headings. These headings are further divided into more than 5000 6-digit sub-headings, which form the HS Code. National Customs authorities can extend these codes and add any subdivision that they may find necessary. The majority of countries base their tariffs on the HS, however, they may classify down to the 8-digit level or further. To aid the classification of goods, the World Customs Organisation (WCO) produces the following publications: Explanatory Notes to the Harmonised System - this is available as a 4 volume printed set, or on CD-ROM, and comprises the codes and notes to help determine how a particular commodity should be classified. Amending supplements are issued twice a year in order to keep the code updated. Alphabetical Index to the Harmonised System - the Explanatory Notes are set out according to the classification codes. The Alphabetical Index lists commodities by description with their corresponding codes and where they can be found in the Explanatory Notes.