Materials are distributed to Depository Libraries in paper, microfiche, electronic or video format and may be shelved in separate areas. Homer Babbidge Library's primary location for federal documents is Level B. Our collection is shelved in the Superintendent of Documents Classification System (SuDoc.)

The example below shows how the Superintendent of Documents classification number C 61.34: 987 is constructed for the publication U.S. Industrial Outlook for the year 1987:

  Some common agency prefixes in Superintendent of Documents classification numbers include:

A       Agriculture Department
AE     National Archives & Records Administration
C       Commerce Department
          C 3.    Census Bureau
D       Defense Department
HE     Health and Human Services Department
I         Interior Department
          I 19.   U.S. Geological Survey
J       Justice Department
Ju     Judiciary
L        Labor Department
LC     Library of Congress
NAS   National Aeronautics and Space Administration
PrEx  Executive Office of the President (CIA, FBIS, Budget +)
S       State Department
SI      Smithsonian Institution
T       Treasury Department
          T 22.   Internal Revenue Service 
TD     Transportation Department
VA     Veterans Affairs Department
X,Y    Congress
          Y 1.    Bills, Resolutions, House & Senate Reports and more (mostly microfiche)
          Y 3.    Congressional Commissions and other agencies not specifically designated in the Executive Branch (mostly paper)
          Y 4.    Congressional Committees (mostly received in paper)

.1: annual reports
.2: general publications
.3: bulletins
.4: circulars
.5: laws
.6: regulations, rules, and instructions (we have dropped most of these because of interfiling)
.7: releases
.8: handbooks, manuals, and guides
.9: bibliographies and lists of publications
.10: directories
.11: maps and charts
.12: posters (do not receive)
.13: forms (do not receive most)
.14: addresses, lectures
Subsequent numbers are often used for specific titles, as shown in the example C 61.34:

Not illustrated in the call number example for the U.S. Industrial Outlook are related series.
For example:

.4: circulars
.4/A: separates from circulars (numbered)
.4/B: separates from circulars (unnumbered)
.4/2: administrative circulars
.4/3: technical circulars

(There are exceptions and the title used for illustration above is an exception. When U.S. Industrial Outlook was dropped and continued as U.S. Global Trade Outlook, the number used was C 61.34/2: and the CD-ROM product was C 61.34/3: Later, this new title and number were dropped for the continuing publication titled U.S. Industry & Trade Outlook with the call number C 61.48: The agency and bureau stayed the same, but the number designating the title changed completely. This publication, the result of a public-private partnership between the GPO and a private publisher, included information not previously published together so needed a new number designation.)