Image showing an example of Sudoc call number

Reading a SuDoc Call Number

U.S. Government publications are arranged by the Superintendent of Documents (SuDoc) classification number. Publications are grouped together by issuing agency.

HS 8. 8: ED 8 2019


The issuing agency. In this example, it is Homeland Security.
The department of the issuing agency. In this example, it is U.S. Citizenship and Immigration Services. Office of Citizenship.
Title’s designation number
Year of publication

Understanding the Superintendent of Documents System

SuDocs is the "Superintendent of Documents" classification system used for federal government publications. Government depository items are the only items in the library that use this classification system.

The main way to differentiate a SuDoc call number from other classification systems is that a SuDoc number will always have a colon : in the number.

SuDoc numbers are arranged similarly to LC numbers in that they always go in alphabetical and numerical order. However, in SuDocs, any numbers after a decimal . are read as WHOLE numbers, while in LC numbers after a decimal are, well, decimal numbers.

SuDoc: A 10.23 = 23 is a whole number, coming after A 10.3 and before A 10.124.

LC: A 10.23 = .23 is a decimal number, coming after A 10.124 and before A 10.3.


Written by, or adapted from, Vanderbilt University Libraries (CC BY-SA).