Language maintenance, shift, and endangerment are all outcomes of the dynamics of language communities. Language maintenance can be thought of as the survival of a language in a situation where it might be expected to be endangered. Fishman points out the issue of how language maintenance is to be secured and difficult to characterize. Language shift is in some sense the complement of language maintenance: it is what happens when a language is not maintained. The progression of a language into a new setting is traditionally characterized as occurring by migration, infiltration, or diffusion, depending on whether a whole speech community moves to a new location. Language documentation includes all potentially permanent recording of a language. The crucial aim of revitalization is to act positively on the process of transmission of a language from one generation to the next.