At first glance an unformatted MARC record looks like gibberish or computer noise, but after further investigation, it becomes clearer that the MARC record is a highly structured piece of information. In the language of data structures, the MARC record is a hybrid sequential/random access record.
Formerly, the standard provided for bibliographic records in seven different specifications: books, archival and manuscript control, computer files, maps, music, visual materials, and serials. Recently, the MARC standard has undergone "format integration," that is, the seven separate formats for bibliographic data have been integrated into a single format. This means that a cataloger is no longer limited to using fields that have been specified for a particular format, but any field that is appropriate for a given item may be used.
Some definitions that are useful in a discussion of MARC are*:
Fields : Groups of one or more data elements defined and manipulated as a unit, such as the 245 (Title) and 001 (Record number). Each field is identified by a tag.
Indicators : Two characters at the beginning of each field except for control fields. Indicators provide additional information about the field.
Subfields : Data elements within fields. Each subfield is identified by a subfield code, which is composed of a delimiter - often shown as a $ - and a single character.
Tags : Labels for fields. For example "245" is the tag for the Title field.
The MARC record is made up of three parts: the leader, the directory, and the bibliographic data. The leader is always represented by the first 24 characters of each record.
Examples of MARC records (requires Adobe Acrobat Reader):
Book
Manuscript collection
Sound Recording
Serial
* Crawford, Walt. MARC for Library Use. Boston: G.K. Hall & Co., 1989.
Go to the Library of Congress MARC page
last updated on 5/14/01