The data storage format used by the libraries, MARC 21, is a format maintained by the Library of Congress and used by millions of users around the world. A shared format enables the data to be transferred and records to be harvested between libraries. National adaptations of MARC have been developed internationally, but they have been largely abandoned. Finnish libraries used the FINMARC format for over twenty years, from the 1970s to the 2000s. In 2009, the databases of universities and universities of applied sciences were converted to the MARC 21 format. Public libraries started adopting the system immediately after this. The FINMARC system continues to be in use in most special libraries.
The National Library's MARC office maintains the Finnish and Swedish translations of the format, functions as the contact channel to the Library of Congress, provides training and guidance in the use of the format and maintains required versions of the format.
The development of MARC (Machine-Readable Cataloging) started at the Library of Congress in the 1960s. In the 1980s, MARC became USMARC, and in the late 1990s, MARC 21. National applications have been largely abandoned, and MARC 21 has been translated in 21 languages, including Finnish and Swedish.
The MARC format has been a reliable tool for data transfer and harmonised the description practices at libraries. However, its structure is old-fashioned and it does not work in the world of linked data. New data storage methods are being developed internationally; the BIBFRAME project of the Library of Congress being the furthest along in development. It is based on a functional cataloguing model and it enables making links between description entities.