The Machine-Readable Cataloging Record

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The Machine-Readable Cataloging Record

A MARC record is a MAchine-Readable Cataloging record. It is used by various information agencies to exchange bibliographic (and related) information between systems. The principles underlying the MARC record are also applied to authority control, classification, and community information. With the use of fields and subfields as labels for data elements, the retrieval and manipulation of information in automated library systems is possible(3). The term "machine-readable" simply means that a machine - a computer - can read and interpret data. "Cataloging record" is the information traditionally found on the catalog card, though in a MARC record the information included can,and usually does, involve more than the traditional description, subject headings, main and added entries, and classification or call number.

Familiarly, the MARC record is comprised of three parts: the structure, content designation, and data content; each is discussed throughout this site.

The less familiar information in the MARC record includes its leader and directory. This information precedes the more commonly known bibliographic data elements, and is primarily used by the computer for purposes of designation. The leader includes the first 24 characters (00-23) of the record, each having been assigned a particular meaning, and defines the parameters for processing the record. The directory follows the leader and includes the tag, starting location, and the length of each field within a record.The directory basically turns what is an initially numbing display of confusion (MARC 21 communication format) into the familiar, descending structure we see when viewing the MARC record in an OPAC (2). For an example of what the MARC 21 communications format looks like, click here.

Other less familiar information includes the 008 field, which can be used to search for records by specific measures. This is called "Fixed-Field Codes" and includes abbreviations which indicate such information as textual language, juvenile materials, etc. The purpose of this site, however, is to expound on other, more "accessible" segments of the MARC record, such as the variable control fields and variable data fields(including content designators). This we will do now.

Variable control fields (00X) include data and a field terminator, either a single data element or position-identified fixed-length data elements (in the case of the last variable field in any given record, both a field terminator and a record terminator are included). Variable data fields include the content designators discussed on the next page. It is the content designators which serve to label and explain the bibliographic record.

First, however, we must be aware of the types of formats that encompass the information related to MARC records. There are five specific formats for five types of inclusive data. They are:

MARC 21 format for Bibliographic Data

MARC 21 format for Authority Data

MARC format for Classification Data

MARC format for Community Information

MARC format for Holdings Data

The MARC 21 format for bibliographic data includes those specifications for encoding various forms of bibliographic data.

The MARC 21 format for authority data includes those specifications for encoding elements that identify or control the content or designation of bibliographic information which may be subject to authority control.

The MARC format for classification data includes those specifications for encoding elements related to classification numbers.

The MARC format for community information includes those specifications for encoding elements pertaining to events, programs, etc., so that this informtion may be included into the public access catalog.

The MARC format for holdings data includes those specifications for encoding elements relevant to holdings and location data (4).

The significance of this information cannot be over-stated. If you look at the information given on the page entitled "Field Tag Formulas," you will see that these distinctions affect the inclusion of certain types of information in their particular fields. In this, the specific formats must be considered as the primary directive for content designation.


	Playing With MARC \| home A Brief History \| The Machine-Readable Cataloging Record \| Content Designators \| Field Tag Formulas \| The Necessity of Standards \| Bibliography The Machine-Readable Cataloging Record A MARC record is a MAchine-Readable Cataloging record. It is used by various information agencies to exchange bibliographic (and related) information between systems. The principles underlying the MARC record are also applied to authority control, classification, and community information. With the use of fields and subfields as labels for data elements, the retrieval and manipulation of information in automated library systems is possible(3). The term "machine-readable" simply means that a machine - a computer - can read and interpret data. "Cataloging record" is the information traditionally found on the catalog card, though in a MARC record the information included can,and usually does, involve more than the traditional description, subject headings, main and added entries, and classification or call number. Familiarly, the MARC record is comprised of three parts: the structure, content designation, and data content; each is discussed throughout this site. The less familiar information in the MARC record includes its leader and directory. This information precedes the more commonly known bibliographic data elements, and is primarily used by the computer for purposes of designation. The leader includes the first 24 characters (00-23) of the record, each having been assigned a particular meaning, and defines the parameters for processing the record. The directory follows the leader and includes the tag, starting location, and the length of each field within a record.The directory basically turns what is an initially numbing display of confusion (MARC 21 communication format) into the familiar, descending structure we see when viewing the MARC record in an OPAC (2). For an example of what the MARC 21 communications format looks like, click here. Other less familiar information includes the 008 field, which can be used to search for records by specific measures. This is called "Fixed-Field Codes" and includes abbreviations which indicate such information as textual language, juvenile materials, etc. The purpose of this site, however, is to expound on other, more "accessible" segments of the MARC record, such as the variable control fields and variable data fields(including content designators). This we will do now. Variable control fields (00X) include data and a field terminator, either a single data element or position-identified fixed-length data elements (in the case of the last variable field in any given record, both a field terminator and a record terminator are included). Variable data fields include the content designators discussed on the next page. It is the content designators which serve to label and explain the bibliographic record. First, however, we must be aware of the types of formats that encompass the information related to MARC records. There are five specific formats for five types of inclusive data. They are: MARC 21 format for Bibliographic Data MARC 21 format for Authority Data MARC format for Classification Data MARC format for Community Information MARC format for Holdings Data The MARC 21 format for bibliographic data includes those specifications for encoding various forms of bibliographic data. The MARC 21 format for authority data includes those specifications for encoding elements that identify or control the content or designation of bibliographic information which may be subject to authority control. The MARC format for classification data includes those specifications for encoding elements related to classification numbers. The MARC format for community information includes those specifications for encoding elements pertaining to events, programs, etc., so that this informtion may be included into the public access catalog. The MARC format for holdings data includes those specifications for encoding elements relevant to holdings and location data (4). The significance of this information cannot be over-stated. If you look at the information given on the page entitled "Field Tag Formulas," you will see that these distinctions affect the inclusion of certain types of information in their particular fields. In this, the specific formats must be considered as the primary directive for content designation.