These products are: coal, coke and briquettes, petroleum, petroleum products and related materials, gas and electric current.

The economic and geographic groupings in accordance with those of the International merchandise trade, table 35 in this issue, although table 35 includes more detailed geographic sub-groups which make up the groupings 'Other developed economies' and 'Developing economies' of this table.

The unit value indices are obtained from national sources, except those of a few countries which the United Nations Statistics Division compiles using their quantity and value figures.

For countries that do not compile indices for fuel imports conforming to the above definition, sub-indices are aggregated to approximate an index of SITC section 3.

Unit value indices obtained from national indices are rebased, where necessary, so that 2000=100. Indices in national currency are converted into U.S. dollars using conversion factors obtained by dividing the weighted average exchange rate of a given currency in the current period by the weighted average exchange rate in the base period. All aggregate unit value indices are current period weighted.

The volume indices are derived from the value data and the unit value indices. All aggregate quantum indices are base period weighted.