Metadata Object Description Schema

The Metadata Object Description Schema (MODS) is an XML-based bibliographic metadata standard developed by the Library of Congress' Network Development and Standards Office. Created in 2002, MODS was designed as a compromise between the complexity of the MARC format used by libraries and the extreme simplicity of Dublin Core metadata. The current version is 3.8 (released September 2022).

MODS carries key data elements from MARC 21 records while using language-based tags instead of numeric field codes, allowing easier mapping between formats. The schema enables both conversion of existing MARC data and creation of original resource descriptions. An international Editorial Committee oversees revisions and schema maintenance, with the Library of Congress maintaining the official standard and providing conversion tools (XSLT crosswalks) for mapping between MODS, MARC, and Dublin Core formats.

Primary implementations occur in digital library projects and institutional repositories, with adoption documented across academic libraries, archives, and digital-collection platforms.