Diatype
The term diatype is sometimes used to describe language variation which is determined by its social purpose (Gregory 1967). In this formulation, language variation can be divided into two categories: dialect, for variation according to user, and diatype for variation according to use (e.g. the specialised language of an academic journal). This definition of diatype is very similar to those of register.
The distinction between dialect and diatype is not always clear; in some cases a language variety may be understood as both a dialect and a diatype.
Diatype is usually analysed in terms of field, the subject matter or setting; tenor, the participants and their relationships; and mode, the channel of communication, such as spoken, written or signed.
Read more about this topic: Register (sociolinguistics)