Traditionally libraries have exchanged metadata in domain specific formats such as MARC (MAchine Readable Cataloging) and offered some limited text based download formats to end users. In the latter case there has been limited standardisation although some library OPACs have supported personal bibliographic citation management tools such as EndNote.
More recently, libraries have begun to offer metadata in less proprietary formats (e.g. RDF), often as part of open data initiatives designed to make their metadata more accessible to wider user communities.
Last update: 5 December 2017