To characterize a linguistic level L, the systematic use of complex symbols is rather different from the system of base rules exclusive of the lexicon. So far, the theory of syntactic features developed earlier does not affect the structure of a general convention regarding the forms of the grammar. To provide a constituent structure for T(Z,K), a descriptively adequate grammar is unspecified with respect to the extended c-command discussed in connection with (34). It must be emphasized, once again, that a case of semigrammaticalness of a different sort cannot be arbitrary in nondistinctness in the sense of distinctive feature theory. However, this assumption is not correct, since the earlier discussion of deviance is not quite equivalent to problems of phonemic and morphological analysis.
see also: WikiPedia -- Chomskybot