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Used for U.S. Government Publications

This system of classification groups together publications of government departments, agencies or bureaus with a specific agency being considered the issuing corporate body. The organizational structure of the U.S. government is followed meaning that the subordinate bureaus and division are grouped under the parent organization. Thus U.S. government publications are organized on the shelves by agency--rather than by subject.

The major weakness of the system is that the position of a publication is determined by the current organizational status of the agency at the time that it is issued. When the government is reorganized and the agencies are moved around, the classification numbers also changes. This results in publications of some agencies being scattered and located in different places throughout the classification system.

Not a decimal system
The SuDoc classification system is not a decimal system like the Library of Congress system. Each part of the number is considered a whole number. The periods, slashes, and colons merely divide the parts of the number. For example: A 1.3: files before A 1.223: SuDoc numbers are treated as a sequence of whole numbers.

Class Stem & Basic numbers
The stem is the number to the colon.

For example:

A 57.38: Soil Survey Reports
I 19.3: USGS Bulletins
PREX 3.15: The World Factbook

Basic numbers consists of (1) letters representing a government department or agency followed by (2) a number representing the agency as a whole or a subordinate office. Numbers or letters after a period are usually (3) a series designation followed by a colon, which is then followed by (4) the individual book number.

For example:

Major agency. Sub-Agency. Series: Individual book number
A 13.2:N 49
HE 20.4002:H 88
I 49.2:B 74

Series numbers
All publications are issued in various series. Some have set numbers while others just use the next available number not already assigned. The following are the series most common throughout the number system:

1 = Annual reports
A 1.1: or D 1.1:
2 = General publications (unnumbered publications of a miscellaneous nature)
A 1.2: or HE 20.4002:
3 = Bulletins
I 19.3: or L 2.3:
4 = Circulars
NCU 1.5: or SE 1.5:
6 = Regulations, rules and instructions
HE 20.4006: or SSA 1.6:
7 = Press releases
8 = Handbooks, manuals, guides
C 61.8: or HE 23.3008: or T 70.8:
9 = Bibliographies and lists of publications
LC 17.9:
10 = Directories
SSA 1.10:
11 = Maps and charts
TD 12.11:
12 = Posters
NF 1.12: or PE 1.12:
13 = Forms
SSA 1.13:

Related series
Those that are closely related to an existing series are numbered so that they file next to an earlier series. These often use a slash mark (/) after the initial number or a dash mark (-)

For example:

C 21.5: Official Gazette of US Patents
C 21.5/2: Index of patents

Individual book numbers
These numbers follow the colon and use either numbers or letters in one of following four ways:

1. Unnumbered publications
They are given a two-figure cutter number based on the principal subject word in the title.
NAS 1.2:R 11

If a second publication in the same series is issued with the same principal subject word, a slash is used and the same cutter number is used again followed by a number and so on.
NAS 1.2:R 11/2
NAS 1.2:R 11/3
2. Numbered publications
These use the publication number following the colon.
A 1.35:381

If the publication is revised, a year is now used to indicate the revision date. Earlier collections may have some pieces where the edition number was an edition number.
A 1.35:381/995
A 1.35:381/4
3. Year publications
These are items such as annual reports. They use the year following the colon, but drop the first number. Beginning with the year 2000, all four numbers are used.
D 1.1:996
LC 1.1:2001
W 1.1:899
4. Volumes and issue numbers
For publications issued with volumes and issue numbers, such as a government periodical, the numbering system uses those numbers following the colon
A 43.7:55/3 for v. 55 issue 3

For a longer explanation from the U.S. Government Printing Office, see An Explanation of the Superintendent of Documents Classification System.

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