It is generally recognized that the coal-preparation option for increasing the percentage of compliance coal available should be used whenever that option can be proved favorable on an economic basis. In order to carry out economic evaluations of alternative coal-preparation plants, one should use a revenue requirements approach based on transformations of input coal size distribution vectors into output size distribution vectors containing acceptable Btu, ash and sulfur intensities. Some general procedures are described for tracking energy and other intensities through the more important units used in coal-preparation plants. It is emphasized that there is a need for engineering-oriented algebraic matrix generators paramatized to reflect the steady-state performance of each unit. It is suggested that insufficient attention is being paid to the development of design procedures for plants that process input vectors, and that an interdisciplinary approach would be helpful in order to allow the concepts, models, and methods developed in related disciplines to be shared.