For any transformation which is sufficiently diversified in application to be of any interest, an important property of these three types of EC appears to correlate rather closely with a general convention regarding the forms of the grammar. Conversely, the theory of syntactic features developed earlier raises serious doubts about an abstract underlying order. Furthermore, a subset of English sentences interesting on quite independent grounds does not affect the structure of a descriptive fact. A consequence of the approach just outlined is that the descriptive power of the base component is rather different from a parasitic gap construction. Let us continue to suppose that a case of semigrammaticalness of a different sort does not readily tolerate the strong generative capacity of the theory.
see also: WikiPedia -- Chomskybot