By combining adjunctions and certain deformations, the natural general principle that will subsume this case is necessary to impose an interpretation on a corpus of utterance tokens upon which conformity has been defined by the paired utterance test. In the discussion of resumptive pronouns following (81), the theory of syntactic features developed earlier is not subject to an important distinction in language use. Conversely, the appearance of parasitic gaps in domains relatively inaccessible to ordinary extraction is rather different from an abstract underlying order. So far, this selectionally introduced contextual feature suffices to account for the traditional practice of grammarians. It appears that any associated supporting element is to be regarded as a general convention regarding the forms of the grammar.
see also: WikiPedia -- Chomskybot