MARC standards
| Filename extension | .mrc, .marc |
|---|---|
| Internet media type | application/marc |
MARC (MAchine-Readable Cataloging) standards are a set of digital formats for the description of items catalogued by libraries, such as books. Working with the Library of Congress, American computer scientist Henriette Avram developed MARC in the 1960s to create records that could be read by computers and shared among 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, 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.
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.
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.
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.
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