Library Codes in Germany originate from a project called „Union Catalogue of Prussia“ in the early 20th Century. The then "Auskunftsbureau der deutschen Bibliotheken" (Reference Bureau of the German Libraries) at the Royal Library in Berlin developed the codes further to meet reference and interlibrary loan needs. The first Directory of Library Codes containing more than 300 entries was embedded in the Union Directory of Journals in 1914. Today half of the 14,500 addresses in the ISIL- and Library Code Directory Online bear also a library code.
As library codes are mainly assigned to libraries they are not equally suited for other classes of organisations. Instead, the International Standard Identifier for Libraries and Related Organizations (ISIL) is being used. This identifier is common on an international level and offers a wider range of applications. A complete transfer from library code to ISIL for the German libraries is under planning. Meanwhile both identifiers are being assigned parallel.
Assignment of library codes is carried out on application by the German ISIL- and Library Code Agency. Regarding the assignment it is not mandatory for an organisation to participate in interlibrary loan activities.
Library codes normally will be assigned as consecutive numbers.
1 = Staatsbibliothek zu Berlin - Preußischer Kulturbesitz, Haus Unter den Linden
12 = Bayerische Staatsbibliothek München
100 = Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim
1100 = Kreis- und Stadtbibliothek Osterholz-Scharmbeck
1901 = Stadtbücherei Kolbermoor
• Institute codes (for institute libraries at universities) will be assigned by the university by using the pattern "Code of the university library/number of the institute“. The codes will be reported via application form by the university library and become authoritative through publication within the ISIL- and Library Code Directory Online.
Example: 16/88 = Universität Heidelberg, Institut für Umweltphysik
• Alphabetic character codes were used until 2012 mainly for special academic libraries (in some cases also for other academic libraries, public libraries and other institutions).
B 496 = Stiftung Deutsches Historisches Museum, Bibliothek
M 333 = Bayerisches Hauptstaatsarchiv, Bibliothek
Stg 5 = Linden-Museum Stuttgart, Bibliothek