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Chapter 17. MARC 21 Encoding for Original RDA Data

Chapter Outline

  • Introduction

  • Part I: MARC 21 for Original RDA Entities, Elements, and Relationships

  • Part II: Examples of MARC Records

Key Takeaways

MARC (MAchine Readable Cataloging) formats, which are applications of the ISO 2709 file standard, are the most commonly used encoding schema for the representation and exchange of library cataloging records. There are different variations of MARC as some were developed for regional needs. MARC 21 is currently used by most libraries in North America. UNIMARC is used by many libraries in other countries. Chapter 17 focuses on MARC 21 and the coding of RDA data (bibliographic and authority). A history of the development and a more detailed description of MARC is covered in Chapter 3.

MARC formats

MARC 21 has the following formats: Bibliographic, Authority, Holdings, Classification, Community.


Libraries use MARC Bibliographic, authority, and Holdings formats. Chapter 17 includes examples using Bibliographic and Authority formats only.

MARC records in library catalogs

Although RDA does not include guidance on record structures, it is common practice in MARC 21 (and in most US libraries) to use the bibliographic and authority record structures; however, these structures are not entity-based structures. For example, a MARC 21 bibliographic record may include elements and relationships that are defined under the original RDA entities work, expression, manifestation, and items, while also including relationships to other entities, such as person, corporate body, and works.

"MARC Must Die"

While the majority of library software available still uses variations of the MARC format, there is an increasing push to implement new XML-based formats due to their increased flexibility. The first author to write about the need to replace MARC was Roy Tennant in his 2002 Library Journal article "MARC Must Die." BIBFRAME is developed as one of the options to replace MARC, other XML options are also available. Even so, more than 20 years later, most libraries still use MARC, and a huge amount of legacy data is stored in MARC records. 

Chapter References/Notes

  1. Library of Congress. (2007, October). MARC code list for languages (2007 ed.). Retrieved from http://

  2. Program for Cooperative Cataloging. (2014). PCC guidelines for the application of relationship designators in bibliographic records. Retrieved from

  3. PCC Standing Committee on Training (SCT). (2015). Training manual for applying relationship designators in bibliographic records. Retrieved from

  4. Library of Congress, Network Development and MARC Standards Office. (1999). MARC 21 format for authority data: Including guidelines for content designation. Washington, DC: Cataloging Distribution Service, Library of Congress.


Additional Readings

Here, you will find readings specific to the contents of this chapter.

You may find more readings about similar topics on the Cataloging and Classification Web Resources and External Training Resources pages

MARC Formats and Standards

"MARC Must Die"
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