Gesture is a complex system and is, as Kendon (1989: 2) puts it:

… a locational system, by which the individual maintains his location to both the gathering of co-present individuals and the physical environment; systems concerned with the production of referentially encoded meanings, … and systems that have to do with the ways in which the individual manages his interaction with the physical environment. Any given piece of behaviour that we might look at.…, say, a phrase of movement, … is not to be classified as belonging exclusively to one or other of the functional systems. Rather, it must be regarded as participating in these systems. Further, it may, and, indeed, usually does, participate in several of these systems simultaneously.