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Guide to Interpreting SuDoc Classification Numbers

Tips for locating US Government Publications shelved using the Superintendent of Documents Classification System

Basic Shelving Rules

The Government Publishing Office provides a complete explanation of the Superintendent of Documents Classification System.  


1. Periods, back slashes, and colons separate each section of a SuDoc Number.  Documents are shelved alphabetically by the letters and then numerically, section by section.

C 1.1:

C 1.2:

C 1.24:

C 2.1:

2. All numbers are shelved as whole numbers, not decimals.

              HE 20.40

              HE 20.108:

              HE 20.3016:

3. Single letters are shelved before multiple letters. Multiple letters are shelved alphabetically, regardless of the number of letters.

              L 2.3: 

              LC 4.7:

              N 11.5:

              NAS 1.21:

              NS 1.2: