The following statement of background and principles for content designation in the MARC 21 formats was approved by the American Library Association's ALCTS/LITA/RUSA Machine-Readable Bibliographic Information Committee (MARBI), in consultation with representatives from United States and Canadian national libraries and designated bibliographic networks. The statement includes the principles under which the MARC 21 formats were developed and constitutes a set of working principles for the ongoing process of format development. This document will be revised as necessary.
Section 1: Introduction
Section 2: General Considerations
Section 3: Structural Features
Section 4: Content Designation
Section 5: Organization of the Record
Section 6: Variable Fields and Tags
Section 7: Variable Control Fields
Section 8: Variable Data Fields
Section 9: Coded Data
Standards and Other Documents Related to MARC 21
Formats
1.2.1. 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).
1.2.2. 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.
1.2.3. The 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. The content of other data elements, e.g., coded data section 9 below), is defined in the MARC 21 formats.
1.3.1. MARC 21 Format for Bibliographic Data contains format specifications for encoding data elements needed to describe, retrieve, and control various forms of bibliographic material. The MARC 21 Format for Bibliographic Data is an integrated format defined for the identification and description of different forms of bibliographic material. MARC 21 specifications are defined for books, serials, computer files, maps, music, visual materials, and mixed material. With the full integration of the previously discrete bibliographic formats, consistent definition and usage are maintained for different forms of material.
1.3.2. MARC 21 Format for Holdings Data contains format specifications for encoding data elements pertinent to holdings and location data for all forms of material.
1.3.3. MARC 21 Format for Authority Data contains format specifications for encoding data elements that identify or control the content and content designation of those portions of a bibliographic record that may be subject to authority control.
1.3.4. MARC 21 Format for Classification Data contains format specifications for encoding data elements related to classification numbers and the captions associated with them. Classification records are used for the maintenance and development of classification schemes.
1.3.5. MARC 21 Format for Community Information provides format specifications for records containing information about events, programs, services, etc. so that this information can be integrated into the same public access catalogs as data in other record types.
1.4.1. Through maintenance and revision, content designation is added to and existing content designation is made obsolete or deleted from formats. Content designation is made obsolete when it is found to be no longer appropriate or when the data element involved is no longer needed. An obsolete content designator may continue to appear in records created prior to the date it was made obsolete. Obsolete content designators are not used in new records. A deleted content designator is one that had been reserved in MARC 21 but had not been defined or one that had been defined but it is known with near certainty that it had not been used.
1.4.2. The principles stated in this document have developed over time. The formats contain exceptions to the principles due to early format development decisions. While many exceptions have been made obsolete, others remain because of the need to maintain upward compatibility of the formats in current development.
2.2. The MARC 21 formats, particularly the bibliographic and authority formats, were initially developed to enable the Library of Congress to communicate its catalog 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 cataloging codes applied in the library community and the requirements of the archives community.
2.3. The MARC 21 formats were designed to facilitate the exchange of bibliographic and related information. An attempt has been made to preserve compatiblity with other national and international formats, e.g., UKMARC and UNIMARC.
2.4. 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 cataloging and as agencies responsible for certain data elements.
2.5.1. Responsible Parties Rule:
2.5.1.1. Unmodified records--The institution identified as the cataloging institution (field 040$a) is considered responsible for data content in the record except for agency-assigned data (see section 2.5.2.1. below). The institution identified as the transcribing institution (field 040$c) is considered responsible for content designation and transcription accuracy for all data.2.5.1.2. Modified records--Institutions identified as cataloging or modifying institutions (field 040$a,$d) are considered collectively responsible for data content in the record except for agency-assigned and authoritative-agency data (see section 2.5.2. below). Institutions identified as transcribing or modifying institutions (field 040$c,$d) are considered collectively responsible for content designation and transcription accuracy.
2.5.2. Exceptions to Responsible Parties Rule:
2.5.2.1. Certain data elements are defined in the MARC 21 formats as being exclusively assigned by particular agencies, e.g., International Standard Serial Number (field 022), Library of Congress Control Number (field 010). The content of such agency-assigned elements is always the responsibility of the agency.2.5.2.2. Certain data elements have been defined in the MARC 21 formats in relation to one or more authoritative agencies that maintain the lists or rules upon which the data is based, e.g., Library of Congress Call Number (field 050), National Library of Medicine Call Number (field 060). Where it is possible for other agencies to create similar or identical content for these data elements, content designation may be provided to distinguish between content actually assigned by the authoritative agency and that assigned by other agencies. In the former case, responsibility for content rests with the authoritative agency. In the latter case, the Responsible Parties Rule applies, and no further identification of the assigning agency is provided.
2.6.1. Information which applies only to some copies (or even to a single copy) of a title may be of interest beyond the institutions holding such copies. The MARC 21 formats provide limited content designation for the encoding of this information and for identifying the holding institution, e.g., subfield $5 in the 700-740 added entry fields in the bibliographic format.
2.6.2. Information that does not apply to all copies of a title, and is not of interest to other institutions, is coded in local fields. For instance, the 59X block is reserved for local notes in the bibliographic format (see section 6.7. below).
2.7. Although a MARC record is usually autonomous, data elements are provided that contain information used to link related records. These linkages may be implicit, through identical access points in each record, or explicit, through a linking entry field. The 76X-78X linking entry fields in the bibliographic format may contain either selected data elements that identify the related item or a control number that identifies the related record. In addition, an explicit code in the leader identifies a record that is linked to another record through a control number.
3.2. All information in a MARC record is stored in character form. MARC communications records are coded in Extended ASCII, as defined in the MARC 21 Specifications for Record Structure, Character Sets, and Exchange Media.
3.3. The length of each variable field can be determined either from the length-of-field portion of the directory entry or from the occurrence of the field terminator character [1E(16), 8-bit]. The length of a record can be determined either from the logical record length element in Leader/00-04 or from the occurrence of the record terminator character [1D(16), 8-bit]. The location of each variable field is explicitly stated in the starting character position element in its directory entry.
4.2.1. Display--the formatting of data for screen display, for printing on 3x5 cards or in book catalogs, for production of COM catalogs, or for other visual presentation of the data.
4.2.2. Information retrieval--the identification, categorization, and retrieval of any identifiable data element in a record.
4.3. Some fields serve multiple functions. For example, field 245 (Title Statement) serves both as the bibliographic transcription of the title and the statement of responsibility and as an access point for the title.
4.4. The MARC 21 formats provide for display constants. A display constant is a term, phrase, and/or spacing or punctuation convention that may be system generated under prescribed circumstances to make a visual presentation of data in a record more meaningful to a user. Such display constants are not carried in the data, but may be supplied for display by the processing system. For example, subfield $x in Series Statement field 490 (and in some other fields) implies the display constant ISSN; also, the combination of tag 780 (Preceding Entry) and second indicator value 2 implies the display constant Supersedes.
4.5. The MARC 21 formats support the sorting of data only to a limited extent. In general, sorting must be accomplished through the application of external algorithms to the data.
5.2. 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.
5.3. 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. The directory ends with a field terminator character.
5.4. 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 (see sections 7 and 8 below). 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).
6.2. According to ANSI Z39.2, the tag must consist of alphabetic or numeric ASCII graphic characters, i.e., decimal integers 0-9 or letters A-Z (uppercase or lowercase, but not both). The MARC 21 formats have used only numeric tags.
6.3. The tag is stored in the directory entry for the field, not in the field itself.
6.4.1. Bibliographic format blocks:
0XX = Control information, numbers, codes
1XX = Main entry
2XX = Titles, edition, imprint
3XX = Physical description, etc.
4XX = Series statements
5XX = Notes
6XX = Subject access fields
7XX = Name, etc. added entries or series; linking
8XX = Series added entries; holdings and locations
9XX = Reserved for local implementation
6.4.2. Authority format blocks:
0XX = Control information, numbers, codes
1XX = Heading
2XX = Complex see references
3XX = Complex see also references
4XX = See from tracings
5XX = See also from tracings
6XX = Reference notes, treatment, notes, etc.
7XX = Heading linking entries
8XX = Not defined
9XX = Reserved for local implementation
6.4.3. Holdings format blocks:
0XX = Control information, numbers, codes
1XX = Not defined
2XX = Not defined
3XX = Not defined
4XX = Not defined
5XX = Notes
6XX = Not defined
7XX = Not defined
8XX = Holdings and location data, notes
9XX = Reserved for local implementation
6.4.4. Classification format blocks:
0XX = Control information, numbers, codes
1XX = Classification numbers and terms
2XX = Complex see references
3XX = Complex see also references
4XX = Invalid number tracings
5XX = Valid number tracings
6XX = Notes
7XX = Index terms and number building fields
8XX = Miscellaneous
9XX = Reserved for local implementation
6.4.5. Community information format blocks:
0XX = Control information, numbers, codes
1XX = Primary names
2XX = Titles, addresses
3XX = Physical information, etc.
4XX = Series information
5XX = Notes
6XX = Subject access fields
7XX = Added entries other than subject
8XX = Miscellaneous
9XX = Reserved for local implementation
6.5.1. In these blocks, certain parallels of content designation are preserved. The following meanings are generally given to the final two characters of the tag:
X00 = Personal names
X10 = Corporate names
X11 = Meeting names
X30 = Uniform titles
X40 = Bibliographic titles
X50 = Topical terms
X51 = Geographic namesFurther content designation (indicators and subfield codes) for data elements subject to authority control are defined consistently across the bibliographic and authority formats. These guidelines apply only to the main range of fields in each block, not to secondary ranges, e.g., the linking entry fields 760-787 in the bibliographic format.
6.5.2. Within fields subject to authority control, data elements may exist which are not subject to authority control and which may vary from record to record containing the same heading, e.g., subfield $e, Relator term.
6.5.3. In fields not subject to authority control, each tag is defined independently. Parallel meanings have been preserved whenever possible.
6.6.1. In the MARC 21 bibliographic format, a specific 5XX note field is defined when at least one of the following is true:
6.6.1.1. Categorical indexing or retrieval is required on the data defined for the note. The note is used for structured access purposes but does not have the nature of a controlled access point.6.6.1.2. Special manipulation of that specific category of data is a routine requirement. Such manipulation includes special print/display formatting or selection/suppression from display or printed product.
6.6.1.3. Specialized structuring of information for reasons other than those given in (a) or (b), e.g., to support particular standards of data content when they cannot be supported in existing fields.
6.6.2. In the MARC 21 authority format, the specifications for notes are covered in the following two conditions:
6.6.2.1. A specific note field is needed when special manipulation of that specific category of data is a routine requirement. Such manipulation includes special print/display formatting or selection/suppression from display or printed product.6.6.2.2. Multiple notes are generally not established to accommodate the same type of information for different types of authorities. Notes are thus not differentiated by or limited to subject, name, or series if the same information applies to more than one type.
6.7.1. The 9XX block is reserved for local implementation.
6.7.2. In general, any tag containing the character 9 is reserved for local implementation within the block structure (see section 6.4. above).
6.7.3. The historical development of the MARC 21 formats has left one exception to this general principle: field 490 (Series Statement) in the bibliographic format. There are several obsolete fields with tags containing the character 9.
7.2. Variable control fields consist of data and a field terminator. They contain neither indicators nor subfield codes (see sections 8.3 and 8.4 below).
7.3. Variable control fields contain either a single data element or a series of fixed-length data elements identified by relative character position.
8.2.1. A three-character tag, stored in the directory entry.
8.2.2. Indicators stored at the beginning of each variable data field, the number of indicators being reflected in Leader/10 (Indicator count).
8.2.3. Subfield codes preceding each data element, the length of the code being reflected in Leader/11 (Subfield code count).
8.2.4. A field terminator following the last data element in the field.
8.3.1. Indicators contain values conveying information that interprets or supplements the data found in the field.
8.3.2. The MARC 21 formats specify two indicator positions at the beginning of each variable data field.
8.3.3. Indicators are defined independently for each field. Parallel meanings are preserved whenever possible.
8.3.4. Indicator values are interpreted independently; meaning is not ascribed to the two indicators taken together.
8.3.5. Indicators may be any lowercase alphabetic or numeric character or a blank (#). Numeric values are defined first. A blank (#) is used in an undefined indicator position or to mean information not provided in a defined indicator position. The blank may have specific meaning when necessary for upward compatibility.
8.3.6. The value 9 is reserved for local implementation.
8.4.1. Subfield codes identify data elements within a field that require (or might require) separate manipulation.
8.4.2. Subfield codes in the MARC 21 formats consist of two characters--a delimiter [1F(16), 8-bit], followed by a data element identifier. A data element identifier may be any lowercase alphabetic or numeric character.
8.4.2.1. Numeric identifiers are defined for parametric data used to process the field, or coded data needed to interpret the field. (Note that not all numeric identifiers defined in the past have followed this specification.)8.4.2.2. Alphabetic identifiers are defined for the separate elements that constitute the data content of the field.
8.4.2.3. The character 9 and the following graphic symbols are reserved for local definition as data element identifiers: ! " # $ % & ' ( ) * + ' - . / : ; < = > ?
8.4.3. Subfield codes are defined independently for each field. Parallel meanings are preserved whenever possible.
8.4.4. Subfield codes are defined for purposes of identification, not arrangement. The order of subfields is specified by content standards, e.g., cataloging rules. In some cases, however, such specifications may be incorporated in the MARC 21 format documentation.
8.4.5. Theoretically, all data elements may be repeated. The nature of the data, however, often precludes repetition. The repeatability/nonrepeatability of each subfield code is defined in the MARC 21 formats.
9.2. Coded values consist of fixed-length character strings. Individual elements within a coded-data field or subfield are identified by relative character position.
9.3. Although coded data occur most frequently in the leader, directory, and variable control fields, any field or subfield may be defined for coded-data elements.
# -- Undefined (element not defined)
n -- Not applicable (element is not applicable to the
item)
u -- Unknown (record creator was unable to
determine value)
z -- Other (value other than those defined for the
element)
| -- Fill character (record creator has chosen not to
provide information)
Historical exceptions do occur in the formats. In particular, the blank (#) often has been defined as not applicable or has been assigned a specific meaning.
Information Interchange Format (ANSI/NISO Z39.2-1994)
Format for Information Exchange (ISO 2709-1996)
MARC 21 Concise Formats
MARC 21 Format for Authority Data
MARC 21 Format for Bibliographic Data
MARC 21 Format for Classification Data
MARC 21 Format for Community Information
MARC 21 Format for Holdings Data
MARC 21 Specifications
for Record Structure, Character Sets, and Exchange Media
MARC Code
List for Languages
MARC Code
List for Countries
MARC Code List
for Geographic Areas
MARC Code
List for Organizations
MARC Code Lists
for Relators, Sources, Descriptive Conventions
Go to:
Library
of Congress