An information society is, broadly speaking, a society in which ‘information is the defining feature’ or, to put this differently, a society where work is information-intensive and most work involves the production, analysis and communication of information. A post-industrial society, as described by Bell, responsible for popularising the notion, is one in which there has been a shift from manufacturing to service industries, science-based industries are central to the economy and a new technical elite has assumed a commanding position.

Compared with municipal law the various methods by which rights and duties may be created in international law are relatively unsophisticated. Within a state, legal interests may be established by contracts between two or more persons, or by agreements under seal, or under the developed system for transferring property, or indeed by virtue of legislation or judicial decisions. International law is more limited as far as the mechanisms for the creation of new rules are concerned. Custom relies upon a measure of state practice supported by opinio juris and is usually, although not invariably, an evolving and timely process. Treaties, on the other hand, are a more direct and formal method of international law creation.

In this chapter, we specify some of the notation that is used throughout the text. Many of these concepts will be described in greater detail in Chapter 13. To provide a common notational framework, we review basic mathematical concepts. We review tools for complex numbers, vectors, and matrices, and the relationship between exponentials and logarithms. We specify notation for integration. We discuss the relationship signal representation in terms of amplitude versus power and linear versus decibel.

We now establish some further results, of general theoretical interest.

Jurisdiction concerns the power of the state under international law to regulate or otherwise impact upon people, property and circumstances and reflects the basic principles of state sovereignty, equality of states and non-interference in domestic affairs. Jurisdiction is a central feature of state sovereignty, for it is an exercise of authority which may alter or create or terminate legal relationships and obligations. It may be achieved by means of legislative, executive or judicial action. In each case, the recognised authorities of the state as determined by the legal system of that state perform certain functions permitted them which affect the life around them in various ways. In the United Kingdom, Parliament passes binding statutes, the courts make binding decisions and the administrative machinery of government has the power and jurisdiction (or legal authority) to enforce the rules of law. It is particularly necessary to distinguish between the capacity to make law, whether by legislative or executive or judicial action (prescriptive jurisdiction or the jurisdiction to prescribe), and the capacity to ensure compliance with such law, whether by executive action or through the courts (enforcement jurisdiction or the jurisdiction to enforce). Jurisdiction, although primarily territorial, may be based on other grounds, for example nationality, while enforcement is restricted by territorial factors.