Superintendent of Documents numbers are assigned to government documents by the U. S. Government Printing Office. These can be applied to paper documents, CD-ROMs, or materials on microfilm or microfiche.
A SuDoc number looks like this:
1. Author Symbol. Every executive department and agency, the Judiciary, Congress, and other major independent establishments have a unique alphabetical identifier. For example:
Documents will be found on the shelf alphabetically by this symbol.
2. Subordinate Offices. Numbers are added to the alphabetic identifiers to distinguish bureaus and offices within major departments. For example, the Agriculture Department as a whole is designated as A1, but the Forestry Service is identified as A13.
3. Series Designations. Each type of publication has an identifying number, and this is followed by a colon. Some of the more common types are:
Note:1., 2., and 3. are collectively called the "Class Stem".
4. Book Numbers. The number following the colon of the Class Stem identifies a specific book, either by series number, annual number, or a number based on the subject of the title.
5. Related Series. A new series which is closely related to an already existing series will be placed next to the original on the shelf and differentiated from it with a slash mark and another letter or number.
SuDoc numbers are found in any library that has a collection of government documents.