FDG is the Grammatical Component of an overall model of verbal interaction in which it is linked to a Conceptual Component, an Output Component, and a Contextual Component.

The Grammatical Component comprises the operations of Formulation and Encoding. Formulation concerns the rules that determine what constitute valid underlying pragmatic and semantic representations in a language. Encoding concerns the rules that convert these pragmatic and semantic representations into morphosyntactic and phonological ones. FDG assumes that both Formulation and Encoding are language-specific, i.e., no universal pragmatic, semantic, morphosyntactic, or phonological categories are postulated until their universality has been demonstrated through empirical research.

The Conceptual Component is responsible for the development of both a communicative intention relevant for the current speech event and the associated conceptualizations with respect to relevant extra-linguistic events, and is thus the driving force behind the Grammatical Component as a whole. The Output Component generates acoustic or signed expressions on the basis of information provided by the Grammatical Component. Its function may be seen as translating the digital information in the grammar into analogue form. The Contextual Component contains a description of the content and form of the preceding discourse, of the actual perceivable setting in which the speech event takes place, and of the social relationships between Participants. This type of information is relevant to many grammatical processes, such as narrative chaining, reflexives, and passives.

Distinguishing features of FDG are:

  1. its taking the Discourse Act as the primary object of analysis;
  2. its top-down architecture -- FDG starts with the speaker’s intention and works down to articulation;
  3. its assumption of four levels of analysis: these are called Interpersonal, Representational, Morphosyntactic and Phonological Levels respectively;
  4. its application of the same layered structure at each of the four levels.

Click here for an application of FDG to the utterance Watch out, there’s a bull in the field!.

For the major presentation of FDG's predecessor, Functional Grammar (FG), see Simon C. Dik, The Theory of Functional Grammar (2 vols., 1997).