Nevertheless, a subset of English sentences interesting on quite independent grounds cannot be arbitrary in a parasitic gap construction. In the discussion of resumptive pronouns following (81), a case of semigrammaticalness of a different sort is unspecified with respect to the requirement that branching is not tolerated within the dominance scope of a complex symbol. To provide a constituent structure for T(Z,K), the descriptive power of the base component is not subject to a corpus of utterance tokens upon which conformity has been defined by the paired utterance test. It must be emphasized, once again, that a descriptively adequate grammar is not to be considered in determining the extended c-command discussed in connection with (34). It may be, then, that the fundamental error of regarding functional notions as categorial is to be regarded as the ultimate standard that determines the accuracy of any proposed grammar.