MARC 21 is a machine-readable cataloging standard developed to facilitate the storage and exchange of bibliographic records among libraries, initially created in the 1960s by Henriette Avram. The standard comprises a structure that includes a leader, directory, and variable fields, encoding various data elements for description and retrieval. Although it streamlines bibliographic control and resource sharing, MARC 21 also faces challenges such as complexity and limited focus on electronic resources.

1. MARC -21 (Machine
Readable Catalogue)
Dr.P.PADMA
Assistant Professor
DOLIS

2. Introduction
A MARC record is a Machine-Readable Cataloguing record. It is a
format standard for the storage and exchange of bibliographic records
and related information in machine. It is a standard for the description
of the digital format of any item. This is a computerized method of
recording the information for cataloguing purpose. These computer
readable cataloguing records will help the computer programs to
search for an display specified pieces of the information stored in a
cataloguing record.

3. Machine-readable
“Machine-readable” means
that one particular type of
machine, a computer, can
read and interpret the data in
the cataloguing record.

4. Catalogue
Record
“Cataloguing record” means a
bibliographic record, or the
information traditionally shown on a
catalogue card. The record includes
(not necessarily in this order):
 a description of the item,
 main entry and added entries,
subject headings, and
the classification or call number.

5. MARC 21
 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.

6. Importance of MARC Format
Prevention of
duplication of work;
1
Better sharing of
bibliographic
resources; and
2
Bibliographic
control at
international level.
3

7. MARC 21 Record System
MARC 21 Record System
 Record structure
 Content designation
 Data content

8. Elements of MARC
 A MARC record involves three elements: the record structure, the content
designation, and the data content of the record.
 The structure of MARC records is an implementation of national and
international standards, e.g., Information Interchange Format (ANSI Z39.2)
and Format for Information Exchange (ISO 2709).
 Content designation, the codes and conventions established to identify
explicitly and characterize further the data elements within a record and to
support the manipulation of those data, is defined in the MARC 21 formats.
 The data content of most data elements is defined by standards outside the
formats, e.g., Anglo-American Cataloguing Rules, Library of Congress Subject
Headings, National Library of Medicine Classification.

9. MARC Record
Strucutre
Design principles for MARC 21
 MARC 21 format is a set of codes and
content designators defined for
encoding a particular type of machine-
readable record.
 The record structure is an
implementation of the international
standard format for Information
exchange(ISO 2709) and its American
counterpart, Bibliographic Information
Interchange (ANSI/NISO Z39.2)

10. MARC: Record Structure
The format of
MARC structure
includes :
Leader Record Directory Variable Field

11. Leader
 The leader is the first 24 characters of the records. Each position has an
assigned meaning, but much of information in the leader is for computer use.
Leader provides information about the ensuing record such as the total length
of the record, type of the record code and the bibliographic level.

12. Record
Directory
 Immediately following the leader, the
directory begins. Directory tells what
variable fields are in the record and
where they are placed. There is a 12
characters record directory for each
variable field. The record directory
helps in the retrieval of select fields
from the record. The directory ends
with a field terminator character

13. Variable Fields
 The variable fields follow the leader and the
directory in the record and consist of control fields
and data fields. Control fields preceded data fields in
the record and are arranged in the same sequence as
the corresponding entries in the directory.

14. Content
Designation
Fixed fields
The variable fields
Tags
Indicators
Delimiters
Subfield Codes

15. Fixed Field
 Each bibliographic record is divided logically into fields.
 There is a field for the author, a field for title information and so on.
 These fields are subdivided into one or more “subfields”. They are represented by
3-digit tags. Many tag field has equip the possibility and responsibility to use
subfield to encode additional information
 The subfield data designated and interpreted by man.

16. Variable data fields
 The remaining variable fields
defined in the format. In addition to
being identified by a field tag in the
Directory, variable data fields
contain two indicator
positions stored at the beginning of
each field and a two-
character subfield code preceding
each data element within the field.

17. Tags
 Each field is associated with 3-digit number called a “tag”.
 A tag identifies the field --the kind of data-- That follows.
 MARC 21 formats use only numeric tags.
 The tag stored in the directory entry for the field, not in the field itself.
 Here the number 100 is the tag 100 1# Sa Pirsig, Robert M.  Variable field tags are defined in
blocks according to the first character of the tag, which with some exceptions, identifies the
general function of the field’s data within a record.
 The type of information in the field is identified by the remainder of the tag.
 The meaning of these blocks depends upon the type of record

18. Indicators
 Digits or blanks that give the computer instructions or information about the data contained in the
field.
 Two character positions follow each tag(with the exception of fields 001 through 009).
 One or both of these character positions may be used for indicators.
 When an indicators position is not used, that indicator is referred to as “undefined” and the
position is left blank
 It is the convention to represent a blank, or undefined, indicator position by the character “

19. Subfield Codes
 Single letters or digits indicate what type of information is in a subfield .
 Subfield are smaller piece of information
 You can have more than one subfield

20. Data
Content
Description
Subject headings
Classification numbers
Main and added entries

21. Advantages of MARC -21
 Easily duplicated and standardized.
 Can carry data formulated by different cataloguing rules and conventions
 Transmits data from one system to another
 Alllow libraries to share authority data that is predictable and reliable
 Can be formatted for any types of library
 Improves ease, efficiency and cooperation

22. Problems with MARC 21
 Not enough focus on electronic resources
 Too complex • Redundant data (fixed Vs. Variable fields)
 Lack of explicit hierarchical levels
 Controlled values embedded in the standard
 Limitation of available fields, subfields, indicator values, etc.
 English language and western oriented

23. Conclusion
 MARC 21 is not a cataloguing standard, it is a Communication standard and
a framework for exchanging catalogue records .MARC 21 = USMARC +
CAN/MARC . MARC 21 developed in 1997-98 & 1st published in 1999 as
named MARC 21 .MARC 21 record acts as a uniform record structure for
the representation of disparate information types .MARC 21 may appear
difficult at first, but with knowledge and use, it will begin to make sense. As
you become more familiar with MARC, the simpler it will become.