[4][5] SuDocs call numbers are assigned by the Government Publishing Office as new publications are produced.
[7] William Leander Post, head of the Government Printing Office's Public Documents Library, assigned new symbols for government agencies, allowing for the expansion of the system to accommodate all federal agencies.
[1][6] SuDocs call numbers consist of two main parts: a class stem, and a suffix.
Boards and agencies created by Congress (versus those created by the Executive Branch) are assigned call numbers beginning with Y 3,[9] and publications of congressional committees are assigned call numbers beginning with Y 4.
Category classes are used to group together the types of publications that federal agencies commonly issue.
[12] The Canadian equivalent of SuDocs is the CODOC system, which was created in 1966 at the University of Guelph.