The U.S. Superintendent of Documents developed this system (also called SuDocs) for the arrangement of federal government publications. Arrangement is generally by issuing agency; for more information see our U.S. SuDoc & Agency List page. Some of the Government Documents collections use this classification system.

SuDocs numbers consist of a letter, designating the particular issuing agency, followed by numbers identifying subordinate bureaus within the agencies and specific publications. Below is a list of prefixes and their corresponding agencies:

• A: Agriculture Department
• C: Commerce Department
• C3: Census Bureau (Commerce Dept.)
• D: Defense Department
• E: Energy Department
• ED: Education Department
• GA: General Accounting Office
• HE: Health and Human Services Department
• I: Interior Department
• I19: U.S.Geological Survey (Interior Department)
• J/Ju: Justice and Judiciary
• L: Labor Department
• LC: Library of Congress
• NAS: National Aeronautics and Space Administration
• S: State Department
• T: Treasury Department
• X,Y: Congress