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=                           MARC_standards                           =
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                            Introduction
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MARC (machine-readable cataloging) is a standard set of digital
formats for the machine-readable 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.


                              History
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Working with the Library of Congress, American computer scientist
Henriette Avram developed MARC between 1965 and 1968, making it
possible to create records that could be read by computers and shared
between libraries.  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 some parts
of 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
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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.


Content
=========
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.


                              Formats
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MARC formats
!Name   !Description
|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 records  |describe the intellectual and physical
characteristics of bibliographic resources (books, sound recordings,
video recordings, and so forth).
|Classification records |MARC records containing classification data.
For example, the Library of Congress Classification has been encoded
using the MARC 21 Classification format.
|Community Information records  |MARC records describing a
service-providing agency, such as a local homeless shelter or tax
assistance provider.
|Holdings records       |provide copy-specific information on a library
resource (call number, shelf location, volumes held, and so forth).


MARC 21
=========
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. 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.

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.


MARCXML
=========
MARCXML is an XML schema based on the common MARC 21 standards.
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. 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:

* Simplicity of the schema
* Flexibility and extensibility
* Lossless and reversible conversion from MARC
* Data presentation through XML stylesheets
* MARC records updates and data conversions through XML
transformations
* Existence of validation tools


                               Future
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The future of the MARC formats is debated by librarians. The storage
formats are quite complex and are based on outdated technology, but
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), which aims
at providing a replacement for MARC that provides greater granularity
and easier re-use of the data expressed in multiple catalogs.
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. The MARC formats are
managed by the MARC Steering Group, which is advised by the MARC
Advisory Committee. 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
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* Cataloging
* International Standard Bibliographic Description (ISBD)
* ISO 2709
* JACKPHY
*  (MAB)
* Metadata and metadata standards
* Z39.50
* ONIX for Books
* Resource Description and Access
* Library of Congress Classification
* Statement of International Cataloguing Principles
* Anglo-American Cataloguing Rules


                             References
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* Reitz, J. M. (2004) [http://www.abc-clio.com/ODLIS/odlis_m.aspx
Online Dictionary for Library and Information Science].


                           External links
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* [https://www.loc.gov/marc/umb/ Understanding MARC Bibliographic
Machine Readable Cataloging], a good introduction
* [http://authorities.loc.gov/help/disphlp1.htm MARC authority
records]
*
* [https://www.loc.gov/marc/faq.html MARC frequently asked questions]
* [https://www.loc.gov/marc/countries/cou_home.html List of MARC
country codes]
* [https://www.loc.gov/marc/ndmso.html Network Development and MARC
Standards Office]
* [https://www.loc.gov/marc/specifications/specchartables.html MARC 21
Character Sets]
*
*
*
[https://web.archive.org/web/20061105215501/http://chopac.org/cgi-bin/tools/az2marc.pl
Amazon to MARC Converter]
* [http://www.dnb.de/EN/Standardisierung/Formate/MAB/mab_node.html MAB
information, Deutsche Nationalbibliothek]
*
[https://web.archive.org/web/20090209042415/http://www.niso.org/kst/reports/standards?step=2&gid=&project_key=fb7a107043228a342cb704973825aca7bc6ae58d
NISO/ANSI Z39.2]
*
[http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=7675|ISO
2709:1996]
* [http://mak.bn.org.pl/wykaz5.htm Converting MARCBN into MARC21]
* [https://www.loc.gov/standards/marcxml/ Library of Congress:
MARCXML]
* [http://xml.coverpages.org/LOC-StandardMARCXML-ShemaAnnounce.html
"Library of Congress Announces Standard MARCXML Schema"]
* [http://journal.code4lib.org/articles/3832/ Interpreting MARC:
Where’s the Bibliographic Data?] by Jason Thomale Code4Lib Journal
Issue 11, 2010-09-21


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