Much work has been done in dialogue modeling for Human - Computer Interaction. Problems arise in situations where disambiguation of highly ambiguous data base output is necessary. We propose to model the task rather than the dialogue itself. Furthermore, we propose underspecified representations to represent relevant data and to serve as a base for generating clarification questions that guide the user eficiently to arrive at his communicative goal. In this paper, we establish a connection between underspecified representations as representations of disjunctions and clarification questions. Our approach to clarifying dialogues differs from other approaches in that the form of the clarification dialogues is entirely determined by the domain modeling and by the underspecified representations.