Rule-based specifications of systems have again become common in the context of product line variability modeling and configuration systems. In this paper, we define a logical foundation for rule-based specifications that has enough expressivity and operational behavior to be practically useful and at the same time enables decidability of important overall properties such as consistency or cycle-freeness. Our logic supports rule-based interactive user transitions as well as the definition of a domain theory via rule transitions. As a running example, we model DOPLER, a rule-based configuration system currently in use at Siemens.