A SuDocs number is a call number used by the U.S. Government’s official classification system, short for Superintendent of Documents. The Superintendent of Documents uses an alpha-numeric classification system that assigns a SuDoc number to each publication. This system classifies each document by an institutional author (such as Congress or a government agency). A SuDoc number is composed of two major parts divided by a colon: the stem, (which identifies the government department or agency that issued the publication) and a book number (which is specific to that document). For more information, check out the FDLP's website.