MARC standards

Last updated
Filename extension
.mrc, .marc
Internet media type

MARC (machine-readable cataloging) standards are a set of digital formats for the description of items catalogued by libraries, such as books, DVDs, and digital resources. Computerized library catalogs and library management software need to structure their catalog records as per an industry-wide standard, which is MARC, so that bibliographic information can be shared freely between computers. The structure of bibliographic records almost universally follows the MARC standard. Other standards work in conjunction with MARC, for example, Anglo-American Cataloguing Rules (AACR)/Resource Description and Access (RDA) provide guidelines on formulating bibliographic data into the MARC record structure, while the International Standard Bibliographic Description (ISBD) provides guidelines for displaying MARC records in a standard, human-readable form.



Working with the Library of Congress, American computer scientist Henriette Avram developed MARC during 1965–1968 to create records that could be read by computers and shared among libraries. [1] [2] By 1971, MARC formats had become the US national standard for dissemination of bibliographic data. Two years later, they became the international standard. There are several versions of MARC in use around the world, the most predominant being MARC 21, created in 1999 as a result of the harmonization of U.S. and Canadian MARC formats, and UNIMARC. UNIMARC is maintained by the Permanent UNIMARC Committee of the International Federation of Library Associations and Institutions (IFLA), and is widely used in Europe.

The MARC 21 family of standards now includes formats for authority records, holdings records, classification schedules, and community information, in addition to the format for bibliographic records.

Record structure and field designations

The MARC standards define three aspects of a MARC record: the field designations within each record, the structure of the record, and the actual content of the record itself.

Field designations

Each field in a MARC record provides particular information about the item the record is describing, such as the author, title, publisher, date, language, media type, etc. Since it was first developed at a time when computing power was low, and space precious, MARC uses a simple three-digit numeric code (from 001-999) to identify each field in the record. MARC defines field 100 as the primary author of a work, field 245 as the title and field 260 as the publisher, for example.

Fields above 008 are further divided into subfields using a single letter or number designation. The 260, for example, is further divided into subfield "a" for the place of publication, "b" for the name of the publisher, and "c" for the date of publication.

Record structure

MARC records are typically stored and transmitted as binary files, usually with several MARC records concatenated together into a single file. MARC uses the ISO 2709 standard to define the structure of each record. This includes a marker to indicate where each record begins and ends, as well as a set of characters at the beginning of each record that provide a directory for locating the fields and subfields within the record.

In 2002, the Library of Congress developed the MARCXML schema as an alternative record structure, allowing MARC records to be represented in XML; the fields remain the same, but those fields are expressed in the record in XML markup. Libraries typically expose their records as MARCXML via a web service, often following the SRU or OAI-PMH standards.


MARC encodes information about a bibliographic item, not information about the content of that item; this means it is a metadata transmission standard, not a content standard. The actual content that a cataloger places in each MARC field is usually governed and defined by standards outside of MARC, except for a handful of fixed fields defined by the MARC standards themselves. Resource Description and Access, for example, defines how the physical characteristics of books and other items should be expressed. The Library of Congress Subject Headings (LCSH) are a list of authorized subject terms used to describe the main subject content of the work. Other cataloging rules and classification schedules can also be used.

MARC formats

MARC formats
Authority records provide information about individual names, subjects, and uniform titles. An authority record establishes an authorized form of each heading, with references as appropriate from other forms of the heading.
Bibliographic recordsdescribe the intellectual and physical characteristics of bibliographic resources (books, sound recordings, video recordings, and so forth).
Classification recordsMARC records containing classification data. For example, the Library of Congress Classification has been encoded using the MARC 21 Classification format.
Community Information recordsMARC records describing a service-providing agency, such as a local homeless shelter or tax assistance provider.
Holdings recordsprovide copy-specific information on a library resource (call number, shelf location, volumes held, and so forth).


MARC 21 was designed to redefine the original MARC record format for the 21st century and to make it more accessible to the international community. MARC 21 has formats for the following five types of data: Bibliographic Format, Authority Format, Holdings Format, Community Format, and Classification Data Format. [3] Currently MARC 21 has been implemented successfully by The British Library, the European Institutions and the major library institutions in the United States, and Canada.

MARC 21 is a result of the combination of the United States and Canadian MARC formats (USMARC and CAN/MARC). MARC 21 is based on the NISO/ANSI standard Z39.2, which allows users of different software products to communicate with each other and to exchange data. [3]

MARC 21 allows the use of two character sets, either MARC-8 or Unicode encoded as UTF-8. MARC-8 is based on ISO 2022 and allows the use of Hebrew, Cyrillic, Arabic, Greek, and East Asian scripts. MARC 21 in UTF-8 format allows all the languages supported by Unicode. [4]


MARCXML is an XML schema based on the common MARC 21 standards. [5] MARCXML was developed by the Library of Congress and adopted by it and others as a means of facilitating the sharing of, and networked access to, bibliographic information. [5] Being easy to parse by various systems allows it to be used as an aggregation format, as it is in software packages such as MetaLib, though that package merges it into a wider DTD specification.

The MARCXML primary design goals included: [6]


The future of the MARC formats is a matter of some debate among libraries. On the one hand, the storage formats are quite complex and are based on outdated technology. On the other, there is no alternative bibliographic format with an equivalent degree of granularity. The billions of MARC records in tens of thousands of individual libraries (including over 50,000,000 records belonging to the OCLC consortium alone) create inertia. The Library of Congress has launched the Bibliographic Framework Initiative (BIBFRAME), [7] which aims at providing a replacement for MARC that provides greater granularity and easier re-use of the data expressed in multiple catalogs. [8] Beginning in 2013, OCLC Research exposed data detailing how various MARC elements have been used by libraries in the 400 million MARC records (as of early 2018) contained in WorldCat. [9] The MARC formats are managed by the MARC Steering Group, which is advised by the MARC Advisory Committee. [10] Proposals for changes to MARC are submitted to the MARC Advisory Committee and discussed in public at the American Library Association (ALA) Midwinter and ALA Annual meetings.

See also

Related Research Articles

The Semantic Web, sometimes known as Web 3.0, is an extension of the World Wide Web through standards set by the World Wide Web Consortium (W3C). The goal of the Semantic Web is to make Internet data machine-readable.

In information science, authority control is a process that organizes information, for example in library catalogs, by using a single, distinct spelling of a name (heading) or a numeric identifier for each topic. The word authority in authority control derives from the idea that the names of people, places, things, and concepts are authorized, i.e., they are established in one particular form. These one-of-a-kind headings or identifiers are applied consistently throughout catalogs which make use of the respective authority file, and are applied for other methods of organizing data such as linkages and cross references. Each controlled entry is described in an authority record in terms of its scope and usage, and this organization helps the library staff maintain the catalog and make it user-friendly for researchers.

Encoded Archival Description (EAD) is a standard for encoding descriptive information regarding archival records.

<span class="mw-page-title-main">Cataloging (library science)</span>

In library and information science, cataloging (US) or cataloguing (UK) is the process of creating metadata representing information resources, such as books, sound recordings, moving images, etc. Cataloging provides information such as author's names, titles, and subject terms that describe resources, typically through the creation of bibliographic records. The records serve as surrogates for the stored information resources. Since the 1970s these metadata are in machine-readable form and are indexed by information retrieval tools, such as bibliographic databases or search engines. While typically the cataloging process results in the production of library catalogs, it also produces other types of discovery tools for documents and collections.

ISO 2709 is an ISO standard for bibliographic descriptions, titled Information and documentation—Format for information exchange.

<span class="mw-page-title-main">Henriette Avram</span> American computer programmer and system analyst

Henriette Davidson Avram was a computer programmer and systems analyst who developed the MARC format, the international data standard for bibliographic and holdings information in libraries. Avram's development of the MARC format in the late 1960s and early 1970s at the Library of Congress had a revolutionizing effect on the practice of librarianship, making possible the automation of many library functions and the sharing of bibliographic information electronically between libraries using pre-existing cataloging standards.

The Metadata Object Description Schema (MODS) is an XML-based bibliographic description schema developed by the United States Library of Congress' Network Development and Standards Office. 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 Metadata Encoding and Transmission Standard (METS) is a metadata standard for encoding descriptive, administrative, and structural metadata regarding objects within a digital library, expressed using the XML schema language of the World Wide Web Consortium (W3C). The standard is maintained as part of the MARC standards of the Library of Congress, and is being developed as an initiative of the Digital Library Federation (DLF).

<span class="mw-page-title-main">NewGenLib</span>

NewGenLib is an integrated library management system developed by Verus Solutions Pvt Ltd. Domain expertise is provided by Kesavan Institute of Information and Knowledge Management in Hyderabad, India. NewGenLib version 1.0 was released in March 2005. On 9 January 2008, NewGenLib was declared free and open-source under GNU GPL. The latest version of NewGenLib is 3.1.1 released on 16 April 2015. Many libraries across the globe are using NewGenLib as their Primary integrated library management system as seen from the NewGenlib discussion forum.

The Information Interchange Model (IIM) is a file structure and set of metadata attributes that can be applied to text, images and other media types. It was developed in the early 1990s by the International Press Telecommunications Council (IPTC) to expedite the international exchange of news among newspapers and news agencies.

Resource Description and Access (RDA) is a standard for descriptive cataloging initially released in June 2010, providing instructions and guidelines on formulating bibliographic data. Intended for use by libraries and other cultural organizations such as museums and archives, RDA is the successor to Anglo-American Cataloguing Rules, Second Edition (AACR2).

A schema crosswalk is a table that shows equivalent elements in more than one database schema. It maps the elements in one schema to the equivalent elements in another.

<span class="mw-page-title-main">Metadata</span> Data about data

Metadata is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including:

Metadata Authority Description Schema (MADS) is an XML schema developed by the United States Library of Congress' Network Development and Standards Office that provides an authority element set to complement the Metadata Object Description Schema (MODS).

A bibliographic record is an entry in a bibliographic index which represents and describes a specific resource. A bibliographic record contains the data elements necessary to help users identify and retrieve that resource, as well as additional supporting information, presented in a formalized bibliographic format. Additional information may support particular database functions such as search, or browse, or may provide fuller presentation of the content item.

In computing, a data definition specification (DDS) is a guideline to ensure comprehensive and consistent data definition. It represents the attributes required to quantify data definition. A comprehensive data definition specification encompasses enterprise data, the hierarchy of data management, prescribed guidance enforcement and criteria to determine compliance.

BIBFRAME is a data model for bibliographic description. BIBFRAME was designed to replace the MARC standards, and to use linked data principles to make bibliographic data more useful both within and outside the library community.

The Maschinelles Austauschformat für Bibliotheken or MAB is a bibliographic data exchange format.


  1. Schudel, Matt. "Henriette Avram, 'Mother of MARC,' Dies". Library of Congress. Retrieved June 22, 2013.
  2. McCallum, Sally H. (2002). "MARC: Keystone for Library Automation". IEEE Annals of the History of Computing. 24 (2): 34–49. doi:10.1109/MAHC.2002.1010068.
  3. 1 2 Joudrey and Taylor, Organization of Information, p. 262
  4. "Character Sets: MARC-8 Encoding Environment: MARC 21 Specifications for Record Structure, Character Sets, and Exchange Media (Library of Congress)".
  5. 1 2 "MARC 21 XML Schema". Library of Congress. Retrieved 2013-12-11.
  6. "MARC XML Design Considerations". 2004-12-30. Retrieved 2013-12-11.
  7. "Bibliographic Framework Initiative". Library of Congress. Retrieved 2 February 2013.
  8. "Bibliographic Framework Initiative Update Forum" (BIBFRAME, Library of Congress). Library of Congress . 2013-11-22. Retrieved 2013-12-11.
  9. "MARC Usage in WorldCat". OCLC Research. 2013. Retrieved April 8, 2015.
  10. "MARC Advisory Committee". Library of Congress. Retrieved January 22, 2018.

Further reading