Bibliographic Management | Factfile

MARC 21

The original MAchine Readable Cataloguing (MARC) format was developed at the Library of Congress in 1965-66. As the usefulness of the format became recognised, national variants were subsequently developed and from the 1980s, the original format became known as US MARC. Later USMARC and CANMARC were 'harmonized' in 1997 and the resulting format was named MARC 21. The British Library adopted MARC 21 as its cataloguing format in June 2004.

MARC 21 is a machine-readable ISO 2709 record format, which uses indicators and subfield identifiers in data fields, to hold data about items of intellectual or cultural content. It has developed from the single format for bibliographic description into a 'family' of formats.

MARC records are composed of three elements: the record structure, the content designation and the data content of the record. The record structure is an implementation of the standard for information interchange (ANSI/NISO Z39.2 and ISO 2709). Thus MARC records have three main components:

Leader: Data elements holding information used in processing the record. The first element in any MARC record.

Directory: A series of entries that record the tag (or field label), length and starting location of every variable field in a record.

Variable fields: Each variable field is identified by a three-character numeric tag.

The content designation is the tags, codes and conventions that identify the data elements within a record. The content of the data elements is usually defined by standards outside the formats: International Standard Bibliographic Description (ISBD), Anglo-American Cataloguing Rules (AACR), the various thesauri for subject headings, and the different classification schemes.

MARC 21 undergoes continuous revision. Discussion papers and proposals for changes to the format(s) are submitted through MARBI [http://www.loc.gov/marc/development.html] and are considered at the Mid-Summer and Mid-Winter meetings of the American Library Association (ALA). UK views on proposed changes are made through the Book Industry Communication (BIC) Bibliographic Standards Technical Sub-group.

• Bibliographic format
• Authority format
• Holdings format
• Classification format
• Community Information format

Bibliographic format

Records in the bibliographic format contain bibliographic information about printed and manuscript text materials, computer files, maps, music, serials, visual materials, and mixed media materials. Bibliographic data commonly includes titles, names, subjects, publication data, notes and information about the physical nature of the item. Fields in this format are:

Authority format

The authority format is used for the following types of records

• Established heading
• Reference (to guide the user to the established heading)
• Subdivision (used as part of an established heading)
• Established heading and subdivision
• Reference and subdivision
• Node label (record contains a term meant to be used in the systematic section of a thesaurus to indicate the logical basis of category sub-division; the term is not used as in indexing term)

Holdings format

This is designed to be a carrier for holdings information on three types of bibliographic items:

• Single-part item
• Multi-part item
• Serial item

Classification format

This is designed to carry information about classification numbers and the captions assigned to them in classification schemes. There are three types of classification record:

• Schedule record: contains a number or number span taken from a schedule.
• Table record: contains a base number that is taken from a table in a schedule.
• Index term record: contains an index term representing a concept, which is not associated with a classification number.
• A classification number may be a single number, a defined number span or a summary number span.

Community Information format

This is designed to carry descriptions of non-bibliographic resources that fulfil the information needs of a community. There are five kinds of community information records:

• Individual (i.e. a person — storyteller, civic leader, etc)
• Organisation (e.g. corporation, club)
• Program or service (e.g. computer literacy training, blood bank)
• Event (e.g. lecture, regularly scheduled meeting)
• Other (e.g. planetarium on a university campus)