Deriving products from a software product line is difficult, particularly when there are many constraints in the variability of the product line. Understanding the impact of variability binding decisions (i.e. of selecting or dismissing features) is a particular challenge: (i) the decisions taken must not violate any variability constraint, and (ii) the effects and consequences of every variability decision need to be understood well. This problem can be reduced significantly with good support both for variability specification and decision making. We have developed an extension of the ADORA language and tool which is capable of modeling and visualizing both the functionality and the variability of a product line in a single model and provides automated reasoning on the variability space. In this paper we describe how our approach supports stepwise, incremental derivation of a product requirements specification from a product line specification. We visualize what has been derived so fa...