History
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 theRecord 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.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.MARC formats
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 TheMARCXML
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 toolsFuture
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), 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
* Cataloging * International Standard Bibliographic Description (ISBD) * ISO 2709 * JACKPHY * (MAB) * Metadata andReferences
* Reitz, J. M. (2004Further reading
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