In 1994,Bachmair, Ganzinger, and Waldmann introduced the hierarchicalsuperposition calculus as a generalization of the superpositioncalculus for black-box style theory reasoning.Their calculus works in a framework of hierarchic specifications.It tries to prove theunsatisfiability of a set of clauses with respect to interpretationsthat extend a background model such as the integers with linear arithmeticconservatively, that is, withoutidentifying distinct elements of old sorts ("confusion") and withoutadding new elements to old sorts ("junk").We show how the calculus can be improved,report on practical experiments,and present a new completeness result fornon-compact classes of background models(i.e., linear integer or rational arithmetic restricted tostandard models).