Library of Congress

The PREMIS (Preservation Metadata: Implementation Strategies) Data Dictionary defines a set of metadata that most repositories of digital objects would need to record and use in order to preserve those objects over the long term. It has its roots in the Open Archival Information System Reference Model but has been strongly influenced by the practical experience of such repositories. While the Data Dictionary can be used with other standards to influence the creation of local application profiles, an XML Schema is provided to allow the metadata to be serialized independently.

PREMIS was initially developed by the Preservation Metadata: Implementation Strategies Working Group, convened by OCLC and RLG, and is currently maintained by the PREMIS Maintenance Activity, lead by the Library of Congress.

MARC is a standard and serialization format for representing bibliographic metadata, originally designed as a way of exchanging bibliographic records between library catalogs. Various different versions have been defined, mostly with national or regional scope, of which MARC 21 is probably the most widely used. There also exists an XML serialization of MARC 21, known as MARCXML.
A standard for encoding archival finding aids using XML in archival and manuscript repositories, implementing the recommendations of the International Council on Archives ISAD(G): General International Standard Archival Description.
The Metadata Object Description Schema (MODS) is a bibliographic metadata standard implemented in XML. It reimplements a subset of the elements of MARC (Machine Readable Cataloging) using language-based tags instead of numeric ones, and groups them somewhat differently. It is intended both as a simplified version of MARC 21 and as a richer alternative to Dublin Core for applications such as metadata syndication/harvesting and the documentation of digital information packages. It was developed in 2002 by the Library of Congress Network Development and MARC Standards Office along with a group of interested experts.