A binding is "ceiling" if the applied duty is lower than the bound duty.  The following example illustrates the difference between "ceiling" bindings and bindings at "prevailing" level.

The CCCN and the HS are structured nomenclatures.  The first two digits of CCCN and HS numbers represent the chapter level. The CCCN comprises 99 chapters and the HS 97 chapters. HS chapter 77 is not used at present.

A uniform tariff adopted by a customs union (e.g. the European Communities) to be assessed on imports entering a region from countries outside the union.

A preferential trade area between Burundi, Comoros, Democratic Republic of Congo (DRC), Djibouti, Egypt, Eritrea, Ethiopia, Kenya, Libya, Madagascar, Malawi, Mauritius, Rwanda, Seychelles, Sudan, Swaziland, Uganda, Zambia, and Zimbabwe. 13 of the COMESA members are part of the COMESA free trade area.