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Understanding Nomenclatures

All queries in WITS are based on the nomenclature (or classification) principle which is therefore crucial when working with WITS.

Nomenclatures in WITS are standard internationally recognized classifications used for trade, tariff, and industry and national income accounts' purposes. These classifications are used by countries and international organizations to standardize the content, format and structure of outputs and make them comparable across countries.

Nomenclatures are revised with time in order to take into account changes in international trade. For example, the Harmonized System (HS) nomenclature has been introduced in 1988 and has been through two major revisions since then. Each version corresponds to an extension overall but some product categories have also been deleted or aggregated with others during the revision process.

Example: HS versions and respective number of products


Starting Year

# of products










In the UN COMTRADE database, data are recorded using several nomenclatures and versions depending on the country/period:

  • SITC since 1962;
  • HS since 1988.

Note that some countries may be still using SITC to report trade information to UNSD COMTRADE.

In TRAINS and IDB, data are recorded using HS only.

Beside these two native (used by countries for reporting) nomenclatures, WITS proposes other nomenclatures. These are called derived nomenclatures. Converting Data Between Nomenclatures shows how to use these derived nomenclatures but for now let's look at how a nomenclature looks.

Next: Exploring nomenclatures

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