The International Telecommunications Union (ITU) administers the planning and regulation of the radio frequency spectrum on a worldwide basis through the World Administrative Radio Conferences.
For planning purposes the world is divided into three regions as shown in Figure 9.1. The boundaries are formed by geographical features suited to the purpose such as seas, high mountain ranges or uninhabited remote areas.
180° 160°140° 120°100° 80° 60° 40° 20°0°20° 40° 60° 80° 100°120°140°160° 180°160°60 °
Figure 9.1 ITU defined regions. For purposes of international allocations of frequencies the world has been divided into three regions
The World Administrative Radio Conferences decide the use of blocks of the spectrum, e.g. sound broadcasting, television, marine communications, and the countries permitted to use the blocks for those allotted purposes.