Type and sort conflicts in semantics are usually resolved by a process of reinterpretation. Recently, Egg (1999) has proposed an alternative account in which conflicts are avoided by underspecification. The main idea is to derive sufficiently relaxed underspecified semantic representations; addition of reinterpretation operators then simply is further specialization. But in principle, relaxing underspecified representations bears the danger of overgeneration. In this paper, we investigate this problem in the framework of CLLS, where underspecified representations are expressed by tree descriptions subsuming dominance constraints. We introduce some novel properties of dominance constraints and present a safety criterion that ensures that an underspecified description can be relaxed without adding unwanted readings. We then apply this criterion systematically to Egg's analysis and show why its relaxation operation does not lead to overgeneration.