The manual offers general instructions on the use of SYSTEM 2000 to retrieve any type of data, and specific instructions on how to retrieve data from the U.S. Geological Survey 's Water Data Sources Directory and Master Water Data Index Data Bases. The manual is divided into five major sections plus six appendixes for reference. Section I contains introductory material, including the purpose and scope of the manual, instructions on how to use the manual, basic computer concepts, and basic SYSTEM 2000 concepts. Section II contains basic instructions on retrieving and displaying data, and section III goes into more complex retrievals. Section IV explains how to make efficient use of techniques developed in sections II and III. Section V summarizes and discusses practical applications, and section IV contains all the appendixes required for reference. (USGS)