Formulated in the late 1970s to specify the requirements of the Operational Flight Program (OFP) of the A-7 aircraft [8], the SCR (Software Cost Reduction) requirements method is a method based on tables for specifying the requirements of software systems. During the 1980s and the early 1990s, many companies, including Bell Laboratories, Grumman, Ontario Hydro, and Lockheed, applied the SCR requirements method to practical systems. Each of these applications of SCR had, at most, weak tool support. To provide powerful, robust tool support customized for the SCR method, we have developed the SCR* toolset. To provide formal underpinnings for the method, we have also developed a formal model which defines the semantics of SCR requirements specifications.