We provide a short review of the literature on design of decentralized control based on weak coupling measures for transfer function models. The notion of diagonal dominance for transfer functions has been suggested as a measure of weak coupling for system decomposition. Various generalizations of this notion for partitioned transfer function matrices are discussed as they pertain to design of decentralized control. Such weak coupling techniques permit a decentralized design procedure based on an approximate decoupled mode. The accuracy of these decoupled approximations for control design is highlighted.