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Unit 5: Management of Library Automation

The MARC 21 formats are communication formats, primarily designed to provide specifications Notes
for the exchange of bibliographic and related information between systems. They are widely
used in a variety of exchange and processing environments. As communication formats, they do
not mandate internal storage or display formats to be used by individual systems.
The MARC 21 formats particularly the bibliographic and authority formats were initially
developed to enable the Library of Congress to communicate its catalogue records to other
institutions. The formats have had a close relationship to the needs and practices of North
American libraries with universal collections. They reflect both the various cataloguing codes
applied in the library community and the requirements of the archives community.

The MARC 21 formats were designed to facilitate the exchange of bibliographic and related
information. An attempt has been made to preserve compatibility with other national and
international formats, e.g., UKMARC and UNIMARC.

Notes National agencies in the United States and Canada (Library of Congress, National
Agricultural Library, National Library of Medicine, United States Government Printing
Office, and National Library of Canada) are given special emphasis and consideration in
the formats because they serve as sources of authoritative cataloguing and as agencies
responsible for certain data elements.

A MARC record consists of three main sections: the leader, the directory, and the variable fields.
The leader consists of data elements that contain coded values and are identified by relative
character position. Data elements in the leader define parameters for processing the record.
The leader is fixed in length (24 characters) and occurs at the beginning of each MARC
record.
The directory contains the tag, starting location, and length of each field within the record.
Directory entries for variable control fields appear first, in ascending tag order. Entries for
variable data fields follow, arranged in ascending order according to the first character of
the tag. The order of the fields in the record does not necessarily correspond to the order
of directory entries. Duplicate tags are distinguished only by location of the respective
fields within the record. The length of the directory entry is defined in the entry map
elements in Leader/20-23. In the MARC 21 formats, the length of a directory entry is 12
characters.

!
Caution The directory ends with a field terminator character.
The data content of a record is divided into variable fields. The MARC 21 formats distinguish
two types of variable fields: variable control fields and variable data fields. Control and
data fields are distinguished only by structure. The term fixed fields is occasionally used
in MARC 21 documentation, referring either to control fields generally or to specific
coded-data fields, e.g., 007 (Physical Description Fixed Field) or 008 (Fixed-Length Data
Elements).

5.2.2 UNIMARC (Universal MARC Format)

UNIMARC is an international standard maintained by the International Federation of Library
Association and Institutions (IFLA) to facilitate the international exchange of data in

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