Socio-technical studies needed to be carried out at three broad levels - from micro to macro - all of which are interrelated

Primary work systems. These are the systems which carry out the set of' activities involved in an identifiable and bounded subsystem of a whole organization - such as a line department or a service unit... | Whole organization systems. At one limit these would be plants or equivalent self-standing workplaces. At the other, they would be entire corporations or public agencies. They persist by maintaining a steady state with their environment. | Macrosocial systems. These include systems in communities and industrial sectors, and institutions operating at the overall level of a society. They constitute what I have called "domains". (Trist, 1976a; 1979a). One may regard media as socio-technical systems. McLuhan (1964) has shown that the technical character of different media has far-reaching effects on users. The same applies to architectural forms and the infrastructure of the built environment. Although these are not organizations, they are socio-technical phenomena. They are media in Heider's (1942) as well as McLuhan's sense.