To characterize a linguistic level L, the systematic use of complex symbols suffices to account for the strong generative capacity of the theory. Analogously, this analysis of a formative as a pair of sets of features delimits a corpus of utterance tokens upon which conformity has been defined by the paired utterance test. Note that the fundamental error of regarding functional notions as categorial may remedy and, at the same time, eliminate a descriptive fact. On our assumptions, a subset of English sentences interesting on quite independent grounds does not readily tolerate irrelevant intervening contexts in selectional rules. Notice, incidentally, that an important property of these three types of EC is unspecified with respect to nondistinctness in the sense of distinctive feature theory.
see also: WikiPedia -- Chomskybot