The pricing of air freight services is governed by the International Air Transport Association (IATA) who continues to provide an "Official Rates Policy" which they publish under the title of "The Air Cargo Tariff" (TACT) along with their rules governing transportation. The air freight services rates are generally derived from meetings that are held between IATA Regional Tariff Committees and which are subject to international inter-governmental agreements on rate levels by route or country. Those air freight services companies who wish to introduce or apply a new rate require the permission of IATA and these rates can often be subject to the relevant country's government approval. But now generally they are used as guide lines and often no attempt is made by either IATA or governments to actually enforce their use.
However today IATA tariffs are being increasingly ignored by the many air freight services companies on the major routes because there is so much competition on the market, but they still continue to provide a general guideline for those lesser developed markets around the world. Often where most commodities are concerned an air freight services rate of a charge per kilo of cargo is applied (and discounts are provided for volumes over 100 and 500 kilos).
Although there are specific commodity air freight services rates available these are the exception and are lower than normal rates as they are designed to encourage certain types of cargo to be air freighted on specific trade routes.
Also in addition to the specific commodity air freight services rates there are class rates which are for such commodities as human remains, live animals and perishable cargo (fresh food etc) and there are specific rules that need to be applied for calculating the charges for each type of commodity that is shown under this list.