3.2. Country practices in the use of customs and non-customs data sources. For the majority of countries, customs declarations remain the main source of data for the compilation of their international trade statistics (see annex III.A). However, there is a considerable difference in this regard between developed and developing and transitional countries. According to a survey conducted by the United Nations Statistics Division in 2006, only 55 per cent of the developed countries that replied indicated that they use customs declarations as their main data source, compared with almost all (98 per cent) of developing and transitional countries. More developed countries use additional data sources, such as administrative records associated with taxation (58 per cent) and enterprise surveys (59 per cent), as compared with only 22 per cent and 21 per cent for developing and transitional countries, respectively. This is one of the consequences of the abolition of customs controls among countries of the European Union.
3.3. Use of non-customs data sources. More active use of non-customs sources is also due to the fact that certain kinds of transactions do not pass through customs and therefore information about them needs to be obtained from other data sources maintained by other agencies. Table III.A.1 in annex III.A shows that besides customs declarations, countries also use postal records, tax records, currency exchange records, enterprise surveys, aircraft and ship registers, foreign shipping manifests and reports of commodity boards. All these additional data sources can be useful and maybe necessary in completing the coverage of international merchandise trade statistics. Non-customs sources may be used also for the verification and cross-checking of customs records.
3.4. Transactions frequently not covered by customs records. Transactions of the following items may not appear in customs records:
- Goods delivered through postal or courier services
- Petroleum, gas and water through pipelines
- Border trade (i.e., trade between residents of adjacent areas of bordering countries as stipulated by national legislation)
- Sales and purchases made by aircraft and ships in foreign ports
- Sales and purchases of aircraft, ships and other mobile equipment
- Transactions on the high seas
For these items, the compiling agency will have to use additional data sources to complete the country’s merchandise trade statistics.
 There is no established convention for the designation of countries or areas in the United Nations system “as developed” or “developing”. In common practice, Japan in Asia, Canada and the United States of America in Northern America, Australia and New Zealand in Oceania, and Europe are considered developed regions (see http://mdgs.un.org/unsd/mdg/Host.aspx?Content=Data/RegionalGroupings.htm).