Overview. In concept and design, the HS serves as a basis for a variety of purposes. These include Customs tariffs, the collection of international trade statistics, trade policy, the application of rules of origin, the monitoring of controlled goods, the application of quota controls, the levying of internal taxes and freight tariffs, the collection of transport statistics, and economic research and analysis. It consists of a comprehensive classification system in which all commodities can be classified and identified by a 6-digit HS code. The HS is subject to constant review and is updated every four to six years.