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MARC standards
View on WikipediaThis article may be too technical for most readers to understand. (September 2010) |
| MARC | |
|---|---|
| Filename extension |
.mrc, .marc |
| Internet media type |
application/marc |
MARC (machine-readable cataloging) is a standard set of digital formats for the machine-readable description of items catalogued by libraries, such as books, DVDs, and digital resources. Computerized library catalogs and library management software need to structure their catalog records as per an industry-wide standard, which is MARC, so that bibliographic information can be shared freely between computers. The structure of bibliographic records almost universally follows the MARC standard. Other standards work in conjunction with MARC, for example, Anglo-American Cataloguing Rules (AACR)/Resource Description and Access (RDA) provide guidelines on formulating bibliographic data into the MARC record structure, while the International Standard Bibliographic Description (ISBD) provides guidelines for displaying MARC records in a standard, human-readable form.
History
[edit]Working with the Library of Congress, American computer scientist Henriette Avram developed MARC between 1965 and 1968, making it possible to create records that could be read by computers and shared between libraries.[1][2] 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. UNIMARC is maintained by the Permanent UNIMARC Committee of the International Federation of Library Associations and Institutions (IFLA), and is widely used in some parts of 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.
Record structure and field designations
[edit]The MARC standards define three aspects of a MARC record: the field designations within each record, the structure of the record, and the actual content of the record itself.
Field designations
[edit]Each field in a MARC record provides particular information about the item the record is describing, such as the author, title, publisher, date, language, media type, etc. Since it was first developed at a time when computing power was low, and space precious, MARC uses a simple three-digit numeric code (from 001-999) to identify each field in the record. MARC defines field 100 as the primary author of a work, field 245 as the title and field 260 as the publisher, for example.
Fields above 008 are further divided into subfields using a single letter or number designation. The 260, for example, is further divided into subfield "a" for the place of publication, "b" for the name of the publisher, and "c" for the date of publication.
Record structure
[edit]MARC records are typically stored and transmitted as binary files, usually with several MARC records concatenated together into a single file. MARC uses the ISO 2709 standard to define the structure of each record. This includes a marker to indicate where each record begins and ends, as well as a set of characters at the beginning of each record that provide a directory for locating the fields and subfields within the record.
In 2002, the Library of Congress developed the MARCXML schema as an alternative record structure, allowing MARC records to be represented in XML; the fields remain the same, but those fields are expressed in the record in XML markup. Libraries typically expose their records as MARCXML via a web service, often following the SRU or OAI-PMH standards.
Content
[edit]MARC encodes information about a bibliographic item, not information about the content of that item; this means it is a metadata transmission standard, not a content standard. The actual content that a cataloger places in each MARC field is usually governed and defined by standards outside of MARC, except for a handful of fixed fields defined by the MARC standards themselves. Resource Description and Access, for example, defines how the physical characteristics of books and other items should be expressed. The Library of Congress Subject Headings (LCSH) are a list of authorized subject terms used to describe the main subject content of the work. Other cataloging rules and classification schedules can also be used.
Formats
[edit]| Name | Description |
|---|---|
| Authority records | provide information about individual names, subjects, and uniform titles. An authority record establishes an authorized form of each heading, with references as appropriate from other forms of the heading. |
| Bibliographic records | describe the intellectual and physical characteristics of bibliographic resources (books, sound recordings, video recordings, and so forth). |
| Classification records | MARC records containing classification data. For example, the Library of Congress Classification has been encoded using the MARC 21 Classification format. |
| Community Information records | MARC records describing a service-providing agency, such as a local homeless shelter or tax assistance provider. |
| Holdings records | provide copy-specific information on a library resource (call number, shelf location, volumes held, and so forth). |
MARC 21
[edit]MARC 21 was designed to redefine the original MARC record format for the 21st century and to make it more accessible to the international community. MARC 21 has formats for the following five types of data: Bibliographic Format, Authority Format, Holdings Format, Community Format, and Classification Data Format.[3] Currently MARC 21 has been implemented successfully by The British Library, the European Institutions and the major library institutions in the United States, and Canada.
MARC 21 is a result of the combination of the United States and Canadian MARC formats (USMARC and CAN/MARC). MARC 21 is based on the NISO/ANSI standard Z39.2, which allows users of different software products to communicate with each other and to exchange data.[3]
MARC 21 allows the use of two character sets, either MARC-8 or Unicode encoded as UTF-8. MARC-8 is based on ISO 2022 and allows the use of Hebrew, Cyrillic, Arabic, Greek, and East Asian scripts. MARC 21 in UTF-8 format allows all the languages supported by Unicode.[4]
MARCXML
[edit]MARCXML is an XML schema based on the common MARC 21 standards.[5] MARCXML was developed by the Library of Congress and adopted by it and others as a means of facilitating the sharing of, and networked access to, bibliographic information.[5] Being easy to parse by various systems allows it to be used as an aggregation format, as it is in software packages such as MetaLib, though that package merges it into a wider DTD specification.
The MARCXML primary design goals included:[6]
- Simplicity of the schema
- Flexibility and extensibility
- Lossless and reversible conversion from MARC
- Data presentation through XML stylesheets
- MARC records updates and data conversions through XML transformations
- Existence of validation tools
Future
[edit]The future of the MARC formats is debated by librarians. The storage formats are quite complex and are based on outdated technology, but there is no alternative bibliographic format with an equivalent degree of granularity. The billions of MARC records in tens of thousands of individual libraries (including over 50,000,000 records belonging to the OCLC consortium alone) create inertia. The Library of Congress has launched the Bibliographic Framework Initiative (BIBFRAME),[7] which aims at providing a replacement for MARC that provides greater granularity and easier re-use of the data expressed in multiple catalogs.[8] Beginning in 2013, OCLC Research exposed data detailing how various MARC elements have been used by libraries in the 400 million MARC records (as of early 2018) contained in WorldCat.[9] The MARC formats are managed by the MARC Steering Group, which is advised by the MARC Advisory Committee.[10] Proposals for changes to MARC are submitted to the MARC Advisory Committee and discussed in public at the American Library Association (ALA) Midwinter and ALA Annual meetings.
See also
[edit]References
[edit]- ^ Schudel, Matt. "Henriette Avram, 'Mother of MARC,' Dies". Library of Congress. Retrieved June 22, 2013.
- ^ McCallum, Sally H. (2002). "MARC: Keystone for Library Automation". IEEE Annals of the History of Computing. 24 (2): 34–49. doi:10.1109/MAHC.2002.1010068.
- ^ a b Joudrey and Taylor, Organization of Information, p. 262
- ^ "Character Sets: MARC-8 Encoding Environment: MARC 21 Specifications for Record Structure, Character Sets, and Exchange Media (Library of Congress)". loc.gov.
- ^ a b "MARC 21 XML Schema". Library of Congress. Retrieved 2013-12-11.
- ^ "MARC XML Design Considerations". Loc.gov. 2004-12-30. Retrieved 2013-12-11.
- ^ "Bibliographic Framework Initiative". Library of Congress. Retrieved 2 February 2013.
- ^ "Bibliographic Framework Initiative Update Forum" (BIBFRAME, Library of Congress). Library of Congress. 2013-11-22. Retrieved 2013-12-11.
- ^ "MARC Usage in WorldCat". OCLC Research. 2013. Archived from the original on April 14, 2015. Retrieved April 8, 2015.
- ^ "MARC Advisory Committee". Library of Congress. Retrieved January 22, 2018.
- Reitz, J. M. (2004) Online Dictionary for Library and Information Science.
Further reading
[edit]- MARBI (1996). MARC 21 Formats: Background and Principles. Library of Congress.
- Joudrey, Daniel N., Arlene G. Taylor, and David P. Miller (2015). Introduction to Cataloging and Classification. Libraries Unlimited.
{{cite book}}: CS1 maint: multiple names: authors list (link) - Joudrey, Daniel N., and Arlene G. Taylor (2018). The Organization of Information. Libraries Unlimited.
{{cite book}}: CS1 maint: multiple names: authors list (link) - Coyle, Karen (2011-07-25). "MARC21 as Data: A Start". The Code4Lib Journal (14).
- Tennant, Roy (2002-10-15). "MARC must die". Library Journal.
External links
[edit]- Understanding MARC Bibliographic Machine Readable Cataloging, a good introduction
- MARC authority records
- "MARC 21 home page". Library of Congress.
- MARC frequently asked questions
- List of MARC country codes
- Network Development and MARC Standards Office
- MARC 21 Character Sets
- "Tools For MARC Records". Library of Congress.
- Kevin J. Comerford (12 September 1996). "Notes on MARC Format". Newsgroup: bit.listserv.museum-l. Usenet: UPMAIL05.199609120436340817@msn.com.
- Amazon to MARC Converter
- MAB information, Deutsche Nationalbibliothek Archived 2016-04-14 at the Wayback Machine
- NISO/ANSI Z39.2
- 2709:1996
- Converting MARCBN into MARC21
- Library of Congress: MARCXML
- "Library of Congress Announces Standard MARCXML Schema"
- Interpreting MARC: Where’s the Bibliographic Data? by Jason Thomale Code4Lib Journal Issue 11, 2010-09-21 ISSN 1940-5758
MARC standards
View on GrokipediaHistory and Development
Origins in the 1960s
The development of the MARC (Machine-Readable Cataloging) standards originated in 1965 at the Library of Congress, where a project was initiated to automate library cataloging processes.[11] This effort was spurred by the need to transition from manual card catalogs to machine-readable formats, enabling the efficient sharing of bibliographic data among libraries and reducing redundant cataloging efforts.[11] The project received a $130,000 grant from the Council on Library Resources to support these goals, building on earlier studies from 1963 and 1964 that highlighted the potential for computer-based systems in libraries.[11] Henriette Avram, a programmer and systems analyst at the Library of Congress, played a pivotal role in leading the initiative and defining the basic record layout for machine-readable bibliographic information.[11] In June 1965, Avram authored a key planning memorandum that outlined a standardized format for catalog records, which was reviewed by over 150 Library of Congress staff members to ensure practicality. Her work focused on creating a structure that could accommodate the complexities of cataloging data while facilitating automated processing and distribution. Early prototypes emerged in 1966 through the MARC Pilot Project, which tested the feasibility of the format using experimental media such as magnetic tape.[11] These pilots involved initial distributions of encoded records starting in September 1966, allowing participating libraries to evaluate the system's potential for real-world application. The project achieved its first operational distribution service in 1968, marking a significant milestone with approximately 50,000 bibliographic records distributed by June 30 of that year through weekly releases on magnetic tapes.[11] Collaborations were essential to this phase, with the Library of Congress partnering with 16 institutions, including the New York State Library and the New England Library Information Network, to refine and implement the format.[11] These efforts laid the groundwork for broader adoption, evolving into formal national standards in subsequent years.Standardization and International Adoption
The MARC format attained national standard status in the United States in 1971 through its adoption as ANSI Z39.2 by the American National Standards Institute, establishing a codified structure for the interchange of machine-readable bibliographic data on magnetic tape. This approval formalized the format's role in enabling efficient data sharing among libraries and information systems, building on early prototypes from the 1960s.[12] Internationally, MARC gained recognition in 1973 when the International Organization for Standardization adopted ISO 2709, which incorporated the MARC record structure as the foundation for bibliographic information exchange. This standard promoted compatibility across borders, allowing diverse national systems to communicate effectively without requiring extensive reformatting.[12] Significant milestones followed, including the establishment of the MARC Development Office at the Library of Congress in 1970 to coordinate ongoing format maintenance and distribution services.[13] During the 1980s, the format expanded to accommodate authority records, with specifications for name and subject authorities refined for broader application, and holdings data, culminating in the USMARC Format for Holdings and Locations in 1986 to support detailed inventory management. By 1980, MARC had achieved widespread use in U.S. libraries, powering automated cataloging in major institutions and networks like the Library of Congress and regional consortia.[14][7][15][3] MARC's influence extended to Europe, where it inspired the creation of UNIMARC in 1977 by the International Federation of Library Associations and Institutions as a universal exchange format aligned with ISO 2709 and derived from MARC's core principles to address international bibliographic needs.[16][17]Core Record Structure
Leader and Directory Components
The Leader in a MARC 21 record is a fixed-length field consisting of 24 character positions (00-23) located at the beginning of the record, which provides essential control information for processing the record by systems.[18] It contains numeric and coded values that define parameters such as the overall record length, status, type, and structural elements like the number of indicators per field.[19] This fixed structure ensures consistent machine-readable interpretation across bibliographic, authority, holdings, and other MARC formats.[12] Character positions 00-04 specify the logical record length as a right-justified five-digit numeric value (with leading zeros if necessary), representing the total number of characters in the entire record, including the Leader itself, the Directory, all variable fields, and terminators.[12] Position 05 indicates the record status using a single alphabetic code, such as 'n' for a new record, 'c' for corrected or revised, 'd' for deleted, or 'a' for an increase in encoding level.[20] Position 06 denotes the type of record, for example, 'a' for language material (books), 'g' for maps, or 'm' for computer files in bibliographic records.[19] Positions 17-23 include the encoding level (position 17, such as ' ' for full level or '4' for core level), descriptive cataloging form (position 18), and entry map details like indicator count (position 10, typically '2'), subfield code count (position 11, typically '2'), base address of data (positions 12-16), length of field portion in directory (position 20, typically '4'), and length of starting position portion (position 21, typically '5').[18][19] Following the Leader, the Directory is a variable-length index that begins at position 24 and precedes the variable fields, serving as a navigational map for the record's content.[12] It comprises a series of fixed-length entries, each exactly 12 characters long, one for every variable field in the record (excluding the Leader), and ends with a field terminator character (ASCII 1F hexadecimal).[12] Each entry includes a three-character tag (positions 00-02, numeric or alphabetic to identify the field), a four-character field length (positions 03-06, right-justified numeric up to 9999 characters), and a five-character starting position (positions 07-11, relative to the base address of data, right-justified with zeros).[12] The Leader and Directory together enable efficient parsing of MARC records by allowing software to determine the record's total size and locate specific variable fields without sequentially scanning the entire file, a design rooted in the ISO 2709 international standard for information exchange on magnetic tape.[12] This binary-compatible structure supports interchange between library systems while maintaining compatibility with the variable fields that carry the actual bibliographic data.[21]| Leader Position | Description | Example/Content Type |
|---|---|---|
| 00-04 | Record length (5-digit numeric) | 04520 (total characters) |
| 05 | Record status (alphabetic code) | 'n' (new) |
| 06 | Type of record (alphabetic code) | 'a' (books) |
| 17 | Encoding level (alphanumeric code) | ' ' (full) |
| 18 | Descriptive cataloging form (code) | 'c' (ISBD) |
| 20-21 | Directory entry lengths (numeric) | '4' (field length portion), '5' (starting position portion) |
Data Fields and Subfields
In MARC 21 records, the variable-length data is organized into fields tagged with three-digit numeric codes ranging from 001 to 999. These fields are broadly categorized into control fields, designated as 00X (where X represents digits 1 through 9), and data fields, spanning 1XX through 8XX. Control fields contain machine-readable information essential for record processing, such as identifiers and system control numbers, while data fields hold descriptive bibliographic elements like authors, titles, and subjects. Each field type may be either repeatable or non-repeatable, with repeatability defined on a per-field basis to accommodate multiple instances of similar data without redundancy.[7] Control fields (00X) are structured simply, consisting solely of the tag followed by the data content and a field terminator, without indicators or subfields. For instance, field 001 serves as the control number assigned to the record by the originating agency, providing a unique identifier for the entire bibliographic entry. This streamlined format ensures efficient processing of control information, which is critical for catalog maintenance and interchange.[7] Data fields (1XX-8XX), in contrast, include two indicator positions immediately following the tag to specify how the field content is indexed or interpreted, followed by optional subfields that break the data into granular components. Subfields are delimited by a subfield code consisting of an ASCII 1F (represented as a for the primary data element (e.g., main entry) and a for the title proper (non-repeatable), c for the statement of responsibility (non-repeatable), enabling precise capture of the work's identification.[7][22] The sequence of variable fields concludes with a field terminator (ASCII 1E hexadecimal) after each field's content, and the entire record is terminated by a record separator (ASCII 1D hexadecimal), signaling the end of the bibliographic data as defined in the ISO 2709 standard underlying MARC 21. This termination structure facilitates reliable parsing and exchange of records between systems.[12]Field Designations and Encoding
Numeric Field Codes and Indicators
In MARC 21, numeric field codes, known as tags, are three-digit numbers ranging from 001 to 999 that identify the type and purpose of each data field in a bibliographic record.[7] These tags are organized into ranges to facilitate systematic cataloging, with specific blocks allocated for categories such as control information, classification, main entries, titles, physical descriptions, notes, subjects, and added entries.[9] For instance, tags 001-009 are reserved for control numbers and codes, including the primary control number in field 001 and system control numbers in field 003. Tags 010-099 cover classification and call numbers, such as the Library of Congress call number in field 050 or Dewey Decimal Classification in field 082. The range 100-199 designates main entry fields, like personal names in 100 or corporate names in 110, while 600-699 handle subject access entries, including topical terms in 650.[23] Extending to added entries and links, 700-799 include secondary personal and corporate entries, and 800-899 cover series added entries. Tags 900-999 are available for local use by implementing institutions.[7] The following table summarizes key field tag ranges and their primary functions:| Tag Range | Function Category | Examples |
|---|---|---|
| 001-009 | Control numbers and codes | 001 (Control number), 005 (Date and time of update) |
| 010-099 | Classification and call numbers | 050 (Library of Congress call number), 082 (Dewey Decimal Classification) |
| 100-199 | Main entries (personal, corporate, etc.) | 100 (Main entry-personal name), 111 (Main entry-meeting name)[23] |
| 600-699 | Subject access fields | 650 (Subject added entry-topical term), 651 (Subject added entry-geographic name)[24] |
| 700-799 | Added entries | 700 (Added entry-personal name), 710 (Added entry-corporate name) |
| 800-899 | Series added entries and links | 800 (Series added entry-personal name), 830 (Series added entry-uniform title) |
Character Sets and Encoding Standards
The MARC-8 encoding environment serves as the original character encoding scheme for MARC 21 records, introduced in 1968 to support machine-readable cataloging data.[27] It utilizes a 7-bit base structure extended to 8 bits through the invocation of two graphic character sets, G0 and G1, in accordance with ISO 2022 standards, allowing for the representation of Latin scripts, diacritics, and basic non-Roman characters such as those in Greek, Cyrillic, Arabic, Hebrew, and East Asian languages via escape sequences.[28] The repertoire encompasses over 16,000 characters from standard sets like ASCII (default G0) and ANSEL (default G1), along with custom extensions for symbols and combining marks, but remains a closed set with no further expansions planned.[28] In MARC 21 records, the character coding scheme is indicated in Leader position 09, where a blank (space or #) denotes MARC-8 encoding and 'a' specifies UCS/Unicode.[18] This position is essential for proper record interpretation, as it determines the handling of octets per character, escape sequences, and non-spacing marks; for instance, non-default MARC-8 sets are further detailed in field 066.[18] Following the approval of Unicode as a second encoding option in 1998, MARC 21 specifications were updated in 2007 to recommend UTF-8—the sole authorized Unicode encoding form—for enhanced compliance with international standards and full support for global scripts.[29] UTF-8 enables the representation of over 100,000 characters from the Universal Coded Character Set (ISO/IEC 10646), facilitating bidirectional text, precomposed forms, and diverse languages beyond MARC-8's limitations, thus promoting broader interoperability in library systems.[29] Legacy MARC-8 records pose challenges for non-Latin scripts due to incomplete mappings, such as overlaps in ASCII with bidirectional languages like Hebrew and Arabic, and irreversible custom sets like Greek symbols, often requiring normalization or reordering of combining characters during conversion.[30] Conversions from MARC-8 to UTF-8 involve removing escape sequences and field 066 while setting Leader position 09 to 'a', but unmappable characters may necessitate lossy techniques (e.g., substitution with a vertical bar, 7C hex) or lossless methods like Numeric Character References (e.g., &#xXXXX;), with tools relying on official mapping tables to minimize data loss.[30] The reverse process, from UTF-8 to MARC-8, demands restoration of escape sequences and logical-to-visual reordering for bidirectional scripts, highlighting ongoing needs for robust conversion utilities in handling historical data.[30]MARC 21 Specifications
Bibliographic and Authority Records
The MARC 21 Format for Bibliographic Data and the MARC 21 Format for Authority Data represent the core specifications for encoding descriptive metadata in library cataloging systems.[9][31] These formats, harmonized in 1999 from the USMARC and CAN/MARC standards by the Library of Congress and the National Library of Canada, enable the standardized representation of bibliographic information for resources such as books and serials, as well as authority control for names and subjects to ensure consistency across catalogs.[32] The harmonization eliminated differences between the two formats, resulting in a unified edition that supports international interoperability while maintaining separate structures for bibliographic and authority records.[32] Bibliographic records in MARC 21 describe resources like books, serials, and other materials, using a structure that includes a leader, directory, and variable data fields to capture elements such as identifiers, authorship, titles, and subjects.[9] The leader is a 24-character fixed field providing record-level metadata, such as the record status and type of material; the directory lists the starting position and length of each data field; and data fields are tagged numerically (e.g., 01X-9XX) with subfields (e.g., a978-0-123456-78-9); 100 for the main entry-personal name, identifying the primary author (e.g., 100 1# d1960-); 245 for the title statement, including the title proper and responsibility (e.g., 245 10 cJohn Smith); and 650 for subject added entry-topical term, assigning controlled subjects (e.g., 650 #0 h for media types and enhanced granularity in description fields to align with RDA elements for works, expressions, and manifestations.[33] A sample bibliographic record for a book, as provided by the Library of Congress, illustrates this structure:=LDR *****nam##22*****##a##4500
=001 n 80146242
=003 DLC
=005 19920331092212.7
=008 820305s1991####nyu##########001#0#eng##
=010 ##$a n 80146242 $z ex 86114834
=020 ##$a 0845348116 : $c $29.95
=020 ##$a 0845348205 (pbk.)
=040 ##$a DLC $c DLC $d DLC
=050 00$a PN1992.8.S4 $b T47 1991
=082 00$a 791.45/75/0973
=100 1#$a Terrace, Vincent, $d b. 1948.
=245 10$a Fifty years of television : $b a guide to series and pilots, 1937-1988 / $c Vincent Terrace.
=260 ##$a New York : $b Cornwall Books, $c c1991.
=300 ##$a 864 p. ; $c 24 cm.
=500 ##$a Includes index.
=650 #0$a Television pilot programs $z [United States](/page/United_States) $v Catalogs.
=650 #0$a Television serials $z [United States](/page/United_States) $v Catalogs.
=LDR *****nam##22*****##a##4500
=001 n 80146242
=003 DLC
=005 19920331092212.7
=008 820305s1991####nyu##########001#0#eng##
=010 ##$a n 80146242 $z ex 86114834
=020 ##$a 0845348116 : $c $29.95
=020 ##$a 0845348205 (pbk.)
=040 ##$a DLC $c DLC $d DLC
=050 00$a PN1992.8.S4 $b T47 1991
=082 00$a 791.45/75/0973
=100 1#$a Terrace, Vincent, $d b. 1948.
=245 10$a Fifty years of television : $b a guide to series and pilots, 1937-1988 / $c Vincent Terrace.
=260 ##$a New York : $b Cornwall Books, $c c1991.
=300 ##$a 864 p. ; $c 24 cm.
=500 ##$a Includes index.
=650 #0$a Television pilot programs $z [United States](/page/United_States) $v Catalogs.
=650 #0$a Television serials $z [United States](/page/United_States) $v Catalogs.
=LDR *****nz##22#####n##4500
=001 n 79099376
=003 DLC
=005 20240604000000.0
=008 791007|n|an|anz##|aa |n |u
=010 ##$a n 79099376
=040 ##$a DLC $c DLC
=100 1#$a Cameron, Simon,$d1799-1889
=400 1#$a Cameron, S.$q(Simon)
=670 ##$a His The winning plan, 1860:$b t.p. (Simon Cameron)
=670 ##$a DAB (Cameron, Simon, 1799-1889; Pa. lawyer, Democratic politician)
=670 ##$a WWA, 1607-1896 (Cameron, Simon; b. 1799; d. 1889)
=LDR *****nz##22#####n##4500
=001 n 79099376
=003 DLC
=005 20240604000000.0
=008 791007|n|an|anz##|aa |n |u
=010 ##$a n 79099376
=040 ##$a DLC $c DLC
=100 1#$a Cameron, Simon,$d1799-1889
=400 1#$a Cameron, S.$q(Simon)
=670 ##$a His The winning plan, 1860:$b t.p. (Simon Cameron)
=670 ##$a DAB (Cameron, Simon, 1799-1889; Pa. lawyer, Democratic politician)
=670 ##$a WWA, 1607-1896 (Cameron, Simon; b. 1799; d. 1889)
Holdings and Classification Records
The MARC 21 Format for Holdings Data (MFHD) is a standardized structure for encoding location, circulation, and holdings information for library materials, both serial and nonserial, enabling the communication of detailed item-level data across automated library systems.[36] Established as part of the 1999 MARC 21 consolidation, it superseded earlier USMARC and CAN/MARC holdings formats, incorporating updates from 1991, 1994, and 1998 to align with international standards like ANSI/NISO Z39.71 and ISO 10324 for holdings statements.[36] This format supports the description of physical and digital holdings, including shelving locations, copy numbers, and access conditions, facilitating resource sharing in union catalogs and interlibrary loan networks.[36] Key fields in the holdings format include 852 for location details, such as shelving designations, copy numbers, and institutional addresses; 853 for caption hierarchies defining basic bibliographic units like volumes or issues; and 863 for specific enumeration and chronology data, capturing dates and numbering for held items.[37][38] As a subset of the broader MARC 21 holdings structure, MFHD focuses specifically on machine-readable location and circulation data, allowing libraries to record how items are organized and accessed within collections.[36] Field 856, introduced in 1993, provides electronic location and access, with subsequent enhancements for electronic resources including URLs, access restrictions, and formats for digital materials.[39][40] The MARC 21 Format for Classification Data provides a carrier for encoding classification schedules, numbers, and associated captions, primarily supporting systems like the Library of Congress Classification (LCC) to organize library resources hierarchically.[41] Introduced in 2000 as part of MARC 21, it uses Leader/06 code 'w' to identify records and accommodates scheme-specific conventions via field 084 for classification scheme codes.[41] Central to this format is field 153, which records classification numbers—either single entries or spans—along with captions in subfield e and $f.[42] This enables the maintenance of authoritative classification tables, with headings and subdivisions integrated into the caption structure for precise topical organization.[41] Interoperability between holdings, classification, and bibliographic records is achieved through control fields like 001 (Control Number) and 004 (Control Number for Related Bibliographic Record), allowing holdings and classification data to link directly to corresponding bibliographic entries for comprehensive resource discovery.[36] In systems such as WorldCat, these MARC 21 holdings and classification records support global resource sharing by associating location and organizational data with bibliographic descriptions.[43] MARC 21 formats are periodically updated; the latest, Update No. 40 (June 2025), includes changes such as new subfields in authority and bibliographic fields.[44]Related Formats and Variants
MARCXML and XML Representations
MARCXML is an XML schema developed by the Library of Congress in 2002 to provide a standardized way to serialize and exchange MARC 21 records compliant with the ISO 2709 format in an XML environment.[45][46] This schema enables the representation of binary MARC records in a structured, text-based format, facilitating easier integration with modern web technologies while preserving the original semantics of MARC data.[47] The core structure of MARCXML centers on a root<record> element that encapsulates the entire MARC record. Within this, the leader is represented as a <leader> element containing the fixed-length string data from the original MARC leader. The directory, which maps field positions in binary MARC, is omitted in MARCXML since XML's inherent structure allows direct access to elements; instead, variable fields are encoded as <datafield> elements, each with attributes for the tag (e.g., tag="245"), first indicator, and second indicator. Subfields within datafields are denoted by <subfield> elements with a code attribute (e.g., <subfield code="a">Title</subfield>), ensuring a hierarchical and navigable format. Control fields (00X-0XX) are handled similarly as <datafield> elements without indicators. This design supports lossless round-trip conversion between MARCXML and ISO 2709 binary records.[46]
Key advantages of MARCXML include its human-readable syntax, which contrasts with the opaque binary nature of traditional MARC records, making it more accessible for manual inspection and editing. The schema is inherently extensible, allowing users to add custom XML namespaces or elements for enhancements like linked data integration, such as embedding RDF triples alongside MARC fields. Additionally, MARCXML natively supports UTF-8 encoding, enabling seamless handling of multilingual and non-Latin scripts without the character set limitations of older MARC encodings like MARC-8.[48][49]
In practice, MARCXML is widely used for web services and APIs that require structured metadata exchange, such as digital library catalogs and bibliographic databases. Conversion tools like MARCEdit provide bidirectional mapping between binary MARC files and MARCXML, supporting batch processing, validation, and transformation workflows in library systems. The Library of Congress distributes its MARC 21 records in MARCXML format alongside binary versions, promoting interoperability in networked environments.[50]
