The paper proposes, on the basis of a study of relative clauses and WH-interrogative constructions, to reflect the time-oriented character of the sentence by replacing neutral expressions like "#" with explicit time references like "beginning" and "end." These boundaries are to be universally associated with all phrase types since, apparently, no major type (S, NP, VP) is symmetrically structured. A subsidiary proposal calls for a view of "underlying representation" which would, even under the assumption that all material relevant to semantic interpretation appears in that representation, relax an "all and only" requirement to an "all" so as to admit structurally essential but semantically empty or redundant material. The evidence in support of these proposals arises from: (1) the exclusion of WH-relative pronouns in relative clauses of the type [noun phrase, subordinate clause, head noun] and their obligatory clause-initial positions in relative clauses of the type [noun phrase, head noun, subordinate clause]; and (2) the inadmissability of a pronominal "introducer" in the first type (the prospective clause) as opposed to the admissability of such an introducer in the second (the retrospective clause). The distinct character of the two types can be explained in terms of time-orientation, as that factor reveals itself in WH-interrogatives. (Author/LG)