Metadata Object Description Schema (MODS) is a schema for a bibliographic element set that may be used for a variety of purposes, and particularly for library applications. The standard is maintained by the Network Development and MARC Standards Office of the Library of Congress with input from users. -- More about MODS

MODS 3.6 is the current version of the schema.
MODS 3.6 Changes from version 3.5 is available.