MARC standards

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MARC (Machine-Readable Cataloging) is a library data standard that lets computers read and share catalog records for items like books, DVDs, and digital resources. It helps library systems organize and exchange bibliographic information.

Key ideas
- MARC records are built from fields identified by three-digit numbers. For example, 100 is the main author, 245 is the title, and 260 is publisher information. Fields can have subfields, indicated by letters (for example, 260 subfield a = place, b = publisher, c = date).
- Records are stored in a structured binary format, with markers and a directory that tells software where to find each field and subfield. The ISO 2709 standard defines this structure.
- MARCXML is an XML version of MARC records, created to make sharing easier. MARCXML can be exposed over the web using standards like SRU or OAI-PMH.

How MARC fits with other standards
- MARC is a metadata transmission format, not the content itself. Other standards guide what data goes into MARC records:
- AACR2/RDA provide rules for describing items.
- ISBD gives guidelines for displaying MARC records to humans.
- LCSH (Library of Congress Subject Headings) provides approved subject terms.
- MARC 21 is the main MARC family used in the U.S. and Canada, while UNIMARC is common in Europe.

MARC 21 and formats
- MARC 21 covers several formats: bibliographic, authority, holdings, community, and classification data.
- It supports two character sets: MARC-8 (older, some scripts) and UTF-8 (Unicode, many languages).

MARC history and future
- MARC was developed in the 1960s and became a national, then international standard.
- The Library of Congress introduced MARCXML in 2002 to represent MARC data in XML.
- There is ongoing interest in a new model called BIBFRAME, which aims to make data more flexible and reusable across catalogs.
- Large libraries and networks (like OCLC’s WorldCat) contain billions of MARC records, demonstrating MARC’s continued importance.

Governance
- Changes to MARC are overseen by the MARC Steering Group and the MARC Advisory Committee. Proposals are discussed publicly at major library conferences like the ALA Midwinter and Annual meetings.