Data format or data exchange standards are technical specifications for encoding metadata for machine processing and exchange.
EAD (Encoded Archival Description)
Encoded Archival Description (EAD) is an encoding standard for machine-readable finding aids such as inventories, registers, indexes, and other documents created by archives, libraries, museums, and manuscript repositories. EAD is used in archives, museums, and special collections.
MARC (MAchine Readable Cataloging)
MARC is a metadata standard used as a way to exchange bibliographic data between integrated library systems. MARC is also a data structure standard used for describing bibliographic materials. Primarily the library community uses the MARC format. More information about MARC can be found on the Cataloging Encoding Standards webpage.
METS (Metadata Encoding and Transmission Standard)
The Metadata Encoding and Transmission Standard (METS) is a data encoding and transmission specification expressed in XML. It provides the means to convey metadata necessary for the management of digital objects within a repository and for the exchange of objects between digital repositories. The METS community includes University Libraries, Archives, and Museums. Those institutions which have chosen to register their implementation can be found on the METS Implementation Registry.
MODS (Metadata Object Description Schema)
The Metadata Object Description Schema (MODS) is an XML markup for metadata from existing MARC records as well as original resource description. As MODS is expressed in XML it is more universal than MARC, especially outside the library world. The standard is maintained by the Network Development and MARC Standards Office of the Library of Congress. It is primarily used by libraries and intended for use by library applications. Other uses for MODS can be found by visiting the MODS website.