For designing distillation column control systems, steady state gains as well as transient characteristics, with which control actions such as adjustment of distillate flow rate, influence column product compositions, are of great importance. In this paper the gains are classified and are expressed in compact, closed forms to facilitate pairing controlled variables with manipulated variables in single-loop control systems. It is illustrated that examining gains gives insight in estimating the magnitude of control interactions and that it provides, though limited, a design method for multivariable control systems.