General trade includes all goods that cross the national frontier including goods that are imported into and exported from custom-bonded warehouses and free zones. The general trade system is in use when the statistical territory of a country coincides with its economic territory so that imports include all goods entering the economic territory of a compiling country and exports include all goods leaving the economic territory of a compiling country.

Special trade covers goods that cross the customs frontier plus goods that are imported into and exported from custom-bonded areas. The Special trade system is in use when the statistical territory comprises only a particular part of the economic territory.

– State trading, commercial transactions in military equipment and supplies, foreign aid transactions, improvement and repair trade, transactions in new ships and aircraft, electric energy and gas, and sea products landed direct from the high seas are included in these statistics;

– direct transit trade, temporary imports and exports, transactions in second-hand ships and aircraft, stores and bunkers for ships and aircraft, monetary items, and industrial gold (if the metal content accounts for 80 per cent or more of the total value) are excluded from the statistics. Minor transactions may also be excluded.

These changes necessitate greater vigilance on the part of statistical users because they obviously affect the nature, quality and coverage of the data. In particular, the introduction of Intrastat in 1993 involved a methodological break with the past and affected the quality of the statistics.

- Belgium-Luxembourg Economic Union: Since 1999, Belgium and Luxembourg henceforth publish separate foreign trade results. Belgium-Luxembourg Economic Union statistics are available from 1961 to 1992. Belgium data are available since 1993, while for Luxembourg, which can not provide historical data, data are available since 1999.  

Czech Republic, Hungary, Korea, Mexico, Poland, and Slovak republic: are now Members of the OECD and are presented in this publication as reporting countries. With respect to the available historical data, OECD-Total includes respectively Mexico from 1990, Hungary and Poland from 1992, the Czech Republic from 1993, Korea from 1994 and Slovak Republic from 1997.

Germany: Includes Eastern Germany since January 1991;

Yugoslavia: From 1992 onwards, no longer exists as such. Its constituent countries are Slovenia, Croatia, Serbia, Bosnia-Herzegovina, Montenegro, and Macedonia.

Czechoslovakia: From 1993 onwards, no longer exists as such and has been split into the Czech Republic and the Slovak Republic.

For exports, the trading partner is the country of destination (final) of the goods. For imports, the trading partner is the country of origin or production or consignment. In general, goods obtained entirely from a given country originate in that country; goods produced in two or more countries are deemed to originate in the country where the last transformation or substantial processing took place.

Trade conversion rates (source IMF and UNSD) are used to convert data from national currencies into United States dollars. The exchange rates are the rates provided to the UNSD either by the country concerned or compiled by the IMF. Trade conversion factors are weighted averages of monthly or quarterly exchange rates, the weights being the corresponding monthly or quarterly values of imports and exports. Because of these trade specific calculations, conversion rates of the euro after access ion are different from a country to another.

Users of OECD’s International Trade Statistics databases should note that since February 2002, the national exchange rates for the Euro area countries have been converted into euro.

The option chosen by OECD is to convert exchange rates for periods prior to entry into European Monetary Union (EMU), i.e. prior to 1999 for all members apart from Greece, which acceded in 2001, from the former national currency exchange rate using the appropriate irrevocable exchange rate. Such a conversion facilitates comparisons over time within a country and also preserves the historical evolution (i.e. growth rates). However, pre-EMU euro rates are notional units and are not always suitable to form area aggregates or for cross country comparisons. For further details, see The Statistics Brief Number 2, February 2002 (http://www.oecd.org/statistics, choose Statistics Brief).

Euro Conversion rates

Higher order levels of the classification are derived by addition of lower order levels except where data must be kept confidential at lower levels of aggregation, but may be released at higher levels.

OECD Member States generally apply the principle of passive confidentiality; i.e. they take suitable measures at the request of importers or exporters who feel that their interests would be harmed by the dissemination of data. Confidentiality may concern all data relating to a commodity category, or be limited to the breakdown by partner country; data affected are combined in a line "Secret".

The first step in standardisation is to convert the units in which product quantities are reported by a country for a particular year into one of the eight quantity units used by OECD, namely, : Tons, Cubic Meters, Square meters, Kilometres, Thousands of units, Thousands of pairs, Millions of Kilowatts/Hour, Curies. The second step concerns the aggregation of product quantities to obtain quantities for product groups. Aggregation is straightforward if the quantity unit is the same for all products covered by product group but, if it is not, further standardisation is required.

When quantity units differ within a product group, quantities are converted into the quantity unit of the product with the largest value. The conversion is carried out using the value/quantity ratio of this product. The converted product quantities are not published, they are only used in the aggregation process.

As the example below shows, Community statistics, which cover the European Union as a whole and the statistics compiled by the EU Member States and sent to OECD , which are concerned with the national dimension, are not always directly comparable. There can be methodological differences , which make precise comparison of these statistics impossible.

- Treatment of goods in transit
Some EU Member States, particularly the Netherlands, does not record goods, which they consider to be 'in transit'. This involves, firstly, imports from non-member countries which are cleared in these EU Member States before being dispatched to other EU Member States and, secondly, goods from other EU Member States which are immediately re-exported to non-member countries.

These goods are normally recorded under intra- or extra-EU trade, as appropriate. This phenomenon is known as the 'Rotterdam effect'.

- Other differences
Other methodological differences can cause discrepancies between national statistics received by OECD and Community statistics (examples: classification at national level as 'general trade' rather than 'special trade', or not recording repairs on the grounds that they are services).

Example :
Japanese goods are imported into Europe; they are released for free circulation in Germany, then dispatched to France (EU Member State of consumption). For such an operation, the various recordings will be as follows:

For Community statistics, three operations are recorded:
- import of goods originating in Japan (with Germany as the declaring Member State, since the customs declaration is made there);
- dispatch (intra) from Germany to France;
- arrival (intra) in France from Germany.

For German national statistics, no trade is recorded, as the import from Japan and dispatch to France is regarded as transit.

For French national statistics, goods originating in Japan are entered as imports. France records Japan as the country of origin, as indicated on the Intrastat declaration. This information is considered statistically more relevant at national level

Belgium-Luxembourg Economic Union

As from September 1999, Belgium-Luxembourg as a reporting country has been replaced by Belgium and Luxembourg individually in the calculation of reporting zones. In order to allow you to use Belgium-Luxembourg historical statistics, these have been kept uisng the ISO code XBL.

Nevertheless, it is important to note that, as Belgium statistics are elaborated according to community and not national definitions, Belgium data are higher than Belgium-Luxembourg data (elaborated according to national definitions). Consequently these two kinds of statistics are not comparable.

The following items are included in the statistics:

- Goods in transit in Belgium coming from countries outside EU and bound for other Member States.
- Intra- community arrivals intended for extra-community exports which are registered in Belgium on behalf of export firms resident in other Member State.
- Bilateral trade with Luxembourg
Luxembourg trade with countries other than Belgium is excluded from statistics.