By a "model of grammatical description" is meant a frame of reference within an analyst approaches the grammatical phase of a language and states the results of his investigations. In one sense, there are as many models as there are different descriptions ("grammars" in the sense of monographs). But in another, and very important, sense, most grammatical descriptions seems to cluster about a relatively small number of relatively distinct models [...].
- Hockett (2004b), a pag.110