Background Information

SuDocs class system is an abbreviated title for Superintendent of Documents Classification System. This alphanumeric system was developed between 1895 and 1903 at the Library of the Government Printing Office. It is similar to the archival organizational systems in that is based on the principle of provenance. All publications of a government publisher or issuing agency are grouped together.

There are three major elements to the SuDocs classification number (example used is A 13.3:62/2)

  1. the author symbol (e.g. A 13 is for the Forest Service (13) of the Department of Agriculture(A))
  2. the series designation (e.g. .3: is assigned to Bulletins)
  3. the book number (e.g. 62/2 represents the volume and issue of the Bulletin)

First Component

The author symbol designates the issuing agency or publisher and many not reflect the true author as the name implies. It is composed of two components:
  1. one to four letters representing an executive office or independent agency (e.g. A)
  2. a number representing a subordinate bureau, office, or independent agency (e.g. 13)

Second Component

The second component of the SuDocs number is the series designation. It follows the author symbol and is separated by a period. This number represents the type of information provided by the document (e.g. .3 is a Bulletin, .10 is for Directories, etc.). In order for related series to be shelved adjacent to each other, a slash (/) or a dash (-) may be used.

The author symbol and the series designation comprise the class stem. The stem of the SuDocs number is easily identified because it is everything to the left of the colon. The shelf list cards for check-in are arranged by the class stem.

Third Component

Following the colon is the third component known as the book number. This number, combined with the stem, is unique to each publication. In other words, no two publications will have the same SuDocs number. Documents published prior to the 1980s may use the series number (e.g. No. 8234) for the book number. During the 1980s, the practice of using serial numbers was changed to the last three digits of the year (e.g. 997 for 1997). Publications not using the serial or date have a cuttered book number. In sum, a cuttered number uses a key term in the title to devise an alphanumeric book number. For example, the word Guard would become G93. The nine (9) representing the U and the number three (3) representing the A in the word Guard. Subsequent publications would be extended by a slash (/) and another number, usually sequential (e.g. G93, G93/2, G93/3, etc.).

As in all things, there are exceptions to these rules above.


The SuDocs class system differs from the Library of Congress System largely because the punctuation found in SuDocs numbers (., /, -, :) acts only as separators of each component and subcomponent. For SuDocs numbers, the shelved in this order: date, letters, numbers, words (notice it's alphabetical, d-l-n-w).

The author symbol always begins with the single letter (e.g. A). Multiple digit author symbols are alphabetized by the first letter and then each subsequent letter.


Subordinate agencies of the author symbol are in strict numerical order. In other words:

A 1
A 2
A 3
A 4
A 100
A 101
A 102

The second component, or series designation is preceded by a slash (/). These numbers are always in strict alphabetic or strict numeric order. Numbers lacking a series designation will always be shelved first. For example:

HE 20.3015:
HE 20.3015/2:
HE 20.3015/3:
HE 20.3016:
HE 20.3016:A 24/
HE 20.3016:1

If two publications with the same author symbol and one has an alpha series designation and the other a numeric designation, the alpha number will be shelved first. Like the word alphanumeric implies, the alphabet comes before the numbers. For example:

I 1.69/A:
I 1.69/2:

Book numbers are also arranged in alphanumeric order. Each component of the book number is dealt with individually like the author symbol and series designation. For example:

ED 1.334/2:D 26
ED 1.334/2:D 26/Floppy
ED 1.334/2:D 26/2/Floppy

D 26/Floppy will be shelved after D 26 and before D 26/2/Floppy. The /2 usually designates a different type of publication and therefore, treated as a separate component of the books number. Regardless, documents should be grouped together by like book numbers. In the next example:

GP 3.2:EL 2
GP 3.2:EL 2/997
GP 3.2:EL 2/998
GP 3.2:EL 2/4/997
GP 3.2:EL 2/4/998

Y 4.B 22/3:A 24
Y 4.B 22/3:97-39/PT.1

The 997 or the 998 represents the year published (G.P.O. just leaves off the 1). It is often associated with documents that are published once a year (i.e. annuals). It can also be found on revised publications. In these instances, the year designations are filled sequentially after the primary components of the books number (e.g. EL 2 first and EL 2/998 second). In other words, the year is equivalent to a volume. All of the EL 2s should be grouped together, etc.