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About the German ISIL and Library Code Agency

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 more than 10,000 entries in the ISIL- and Library Code Directory Online carry a library code.

ISIL is the International Standard Identifier for Libraries and Related Organizations (ISO 15511). The ISIL-System is designed for international use and integrates already existing identifiers on national or international level. Since 2004 the German ISIL Agency has been assigning this identifier to organisations in Germany and documents this in the ISIL- and Library Code Directory Online. In many cases the ISIL is derived from the library code system which is more than 100 years old. ISIL- and Library code Agency form one unit.  

Library codes are used 

  • to identify holdings information in union catalogues 
  • as a unique identifier for libraries in the interlibrary lending system

Beyond that ISIL can be used

  • as identifier in RFID technology
  • as code for organisations for machine-readable cataloging in MARC 21
  • as identifier for the originator of a record in authority files


In the medium term Germany aims at a complete change from library code to ISIL in order to make use of the advantages of the latter system and avoid parallel assignment of two identifiers.

The German ISIL and Library Code Agency is part of the department "Überregionale Bibliographische Dienste" in the "Staatsbibliothek zu Berlin".