From C1, it follows that the appearance of parasitic gaps in domains relatively inaccessible to ordinary extraction is unspecified with respect to an abstract underlying order. For any transformation which is sufficiently diversified in application to be of any interest, most of the methodological work in modern linguistics cannot be arbitrary in the levels of acceptability from fairly high (eg (99a)) to virtual gibberish (eg (98d)). To provide a constituent structure for T(Z,K), the earlier discussion of deviance is necessary to impose an interpretation on irrelevant intervening contexts in selectional rules. In the discussion of resumptive pronouns following (81), a descriptively adequate grammar raises serious doubts about the requirement that branching is not tolerated within the dominance scope of a complex symbol. Notice, incidentally, that the notion of level of grammaticalness is not to be considered in determining the strong generative capacity of the theory.
see also: WikiPedia -- Chomskybot