A revised user's guide of the Office of Air Programs (OAP) Economic Model System is presented to facilitate an efficient assessment of control strategies. Air pollution control strategies are first transformed into a set of appropriate model inputs. The computer program accepts these inputs as 'exogenous shocks' to the model system and generates as output, from the model system, measurements of the changes in the key economic variables in the air quality control regions under study. The computer simulation of the Economic Model System includes three programs: Program RMS (Regional Model Simulation), Program 10A (Input-Output Analysis), and Program FBE (Feedback Effects). The report also presents control cost estimates. (Author)