1 Introduction

Chapter contents

1.1  MARC Bibliographic Records
1.2  Input Standards
1.3  Bibliographic Formats
1.4  WorldCat Bibliographic Records
1.5  Cataloging Documentation

Bibliographic Formats and Standards is a guide to bibliographic and holdings information in machine-readable cataloging records in the WorldCat database. It provides tagging conventions, input standards, and guidelines for entering information in this cooperative environment.

WorldCat contains bibliographic records that are descriptions of resources held by or accessible to OCLC member institutions. Bibliographic records are linked with location information, holdings information, authority data, etc.

When working online, catalogers either create original bibliographic records, if no cataloging copy is found, or edit existing records as part of copy cataloging. As part of the cataloging process, catalogers add and delete holdings to indicate if their institution holds or has access to a resource or not. They may add, edit, and delete local holdings records and local bibliographic data.

Members catalog library materials according to current recognized cataloging standards such as Resource Description & Access (RDA) and Anglo-American Cataloguing Rules, 2nd edition (AACR2). Library materials in any language or script may be described in any language of cataloging.

Members may enter older cataloging copy during retrospective conversion. These records may not conform to current standards. Information about other cataloging and coding standards, such as Dublin Core (DC), can be found in section 1.5, Cataloging Documentation.

1.1 MARC Bibliographic Records


The MARC 21 Format for Bibliographic Data is a means for the representation and communication of bibliographic information. MARC stands for MAchine-Readable Cataloging, and is developed and maintained by the Library of Congress, in consultation with the MARC Advisory Committee (MAC), previously known as the MAchine-Readable Bibliographic Information Committee (MARBI).

MARC records consist of three parts:

  • Leader. Contains data elements that primarily provide information for the processing of the record. The data elements contain numbers or coded values and are identified by relative character position. The Leader is fixed in length at 24 character positions and is the first field of a MARC record.
  • 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. Each directory entry is 12 characters long. It is not displayed in OCLC interfaces, but is included in all MARC records exported or output from OCLC.
  • Variable fields. Contains data content divided into variable control fields and variable data fields. OCLC requires that each record have at minimum one variable data field (field 245 with either subfield ǂa or subfield ǂk) in addition to the necessary control fields (Leader, 001, and 008). Inclusion of all other fields is dependent on the resource being cataloged.

The Leader and the 001, 005, and 008 variable control fields are called the OCLC Fixed Field. The fixed field may be displayed as a single area with mnemonic labels for each element or as a separate variable field in Connexion® client and WorldShare Record Manager®.

The variable control fields (001, 005, 006, 007, 008) do not have indicators or subfield codes. In Connexion, OCLC uses subfield codes in field 007 displays to assist with readability and editing; however, the subfield codes are not included or stored in electronic versions of the WorldCat record. In Record Manager, field 007 displays as a variable field and may be clicked on and expanded for guided entry. In MARC 21, field 007 is a control field that does not have indicators or subfield codes.

Variable data fields that identify how data is indexed and displayed in WorldCat vary in number and length. They are identified by the following information:

  • Tag. Three-digit numeric value coded 010 through 999
  • Indicator. Two positions coded with blank or 0 through 9 as possible values
  • Subfield. Textual element identified by a delimiter and a lowercase alphabetic or numeric code

A bibliographic record cannot exceed 99,999 characters. Each variable field cannot exceed 9,999 characters. These limits apply to records exported as MARC 21 using Connexion and Record Manager. If records exceed these limits and need to be exported, the MARCXML export format must be used.


MARC tags identify variable fields and are grouped numerically by function. In the following list, xx stands for a numeric value ranging from 00 to 99:

Tag Group Function
0xx Bibliographic control numbers, coded information, classification, etc.
1xx Primary access points
2xx Titles, edition statements, publication information, etc.
3xx Physical characteristics and arrangement, graphic representation, publication frequency, etc.
4xx Series statements
5xx Notes
6xx Subject access points
7xx Additional access points and linking fields
8xx Series access points, holdings data, etc.
9xx Local use fields


In MARC records, variable field indicators supply information about the field for indexing, display, or other system functions. Variable field indicators may consist of numbers or blanks. Values in the indicator positions, including blanks, have assigned meanings.


Subfields are the smallest logical unit of information in a variable field. Subfield codes (letters or numbers) identify subfields and are preceded by subfield delimiters. In Connexion client the subfield delimiter displays as the Unicode character, alveolar click ( ǂ ), sometimes referred to as a double dagger, while in other OCLC cataloging interfaces the subfield delimiter displays as a dollar sign ( $ ) or double dagger ( ‡ ). The subfield delimiter is coded as ASCII 1F hex in exported records and records delivered via other services.

Subfields contain coded or textual information for the bibliographic description of the resource. In Connexion and Record Manager the display of subfield ǂa is implicit at the beginning of each field, and the subfield code does not display. However, subfield ǂa does display in both cataloging interfaces when it is preceded by another subfield.


MARC 21 is the technical standard for the encoding of bibliographic information. There are some differences between MARC 21 and OCLC's implementation which are noted in this document. For more information about OCLC's implementation, see OCLC-MARC Records.

Some MARC 21 bibliographic data elements have not been implemented by OCLC. This table indicates possible OCLC action to implement them.

MARC 21 Element Name Status
Non-sorting characters N/A No plans to implement in WorldCat bibliographic records.

Note: For more information, see the Control Function Codes section of the MARC 21 Specifications for Record Structure, Character Sets, and Exchange Media: Character Sets and Encoding Options: Part 1: General Character Set Issues.
Leader/17 u - unknown

As part of OCLC’s work on implementing the MARC 21 Encoding Levels to replace the OCLC-defined Encoding Levels, implementation of these values in WorldCat bibliographic records is currently under consideration.

z - not applicable
Leader/19 Multipart resource record level Implementation of the MARC 21 Leader/19 position in WorldCat bibliographic records is currently under consideration.
007 Fill characterfill character ) meaning "No attempt to code"

MARC 21 defines a fill character in every bibliographic 007 position, except for 007/00 (Category of Material, subfield ǂa) and 007/02 (Undefined, subfield ǂc) in each 007 format. In WorldCat, the fill character is not valid in any bibliographic 007 position, but implementation is under consideration.

Blankblank character )

MARC 21 defines a blank in each of the 007 positions listed below. In WorldCat bibliographic records, catalogers using the Connexion client are instructed to omit the subfield in cases where a blank value would be appropriate. Catalogers using Record Manager may leave the default blank characters unchanged in the listed WorldCat bibliographic 007 positions. In WorldCat Local Holdings Records (LHRs), the blank value is valid in all listed 007 positions.

Due to technical limitations in the Connexion record editor, there are no plans to implement the blank in these listed positions in WorldCat bibliographic records.

007 Format 007 Position 007 Subfield Element Definition of Blank
007 (All) 007/02 ǂc Undefined Undefined
007 (Electronic Resource) 007/05 ǂf Sound No Sound (Silent)
007 (Motion Picture) 007/05 ǂf Sound on Medium or Separate No Sound (Silent)
007/06 ǂg Medium for Sound No Sound (Silent)
007 (Nonprojected Graphic) 007/05 ǂf Secondary Support Material No Secondary Support
007 (Projected Graphic) 007/05 ǂf Sound on Medium or Separate No Sound (Silent)
007/06 ǂg Medium for Sound No Sound (Silent)
007/08 ǂi Secondary Support Material No Secondary Support
007 (Tactile Material) 007/03-04 ǂd Class of Braille Writing No Specified Class of Braille Writing
007/06-08 ǂf Braille Music Format No Specified Braille Music Format
007 (Videorecording) 007/05 ǂf Sound on Medium or Separate No Sound (Silent)
007/06 ǂg Medium for Sound No Sound (Silent)
008 Fill characterfill character ) meaning "No attempt to code"

The fill character is valid in all defined MARC 21 Bibliographic 008 positions. In WorldCat, the fill character is not valid in any of the bibliographic 008 positions listed below.  There are no plans to implement the fill character in any of these positions in WorldCat bibliographic records.

008 Position Format Element
008/06 ALL Type of Date/Publication Status (DtSt)
008/07-10 ALL Date 1 (Dates)
008/11-14 ALL Date 2 (Dates)
008/15-17 ALL Country of Publication, etc. (Ctry)
008/21 CNR Type of Continuing Resource (SrTp)
008/22 BKS, COM, REC, SCO, VIS Target Audience (Audn)
008/23 BKS, CNR, COM, MIX, REC, SCO Form of Item (Form)
008/25 MAP Type of Cartographic Material (CrTp)
008/26 COM Type of Computer File (File)
008/28 BKS, CNR, COM, MAP, VIS Government Publication (GPub)
008/29 MAP, VIS Form of Item (Form)
008/30-31 REC, SCO Literary Text for Sound Recordings (LTxt)
008/33 BKS Literary Form (LitF)
VIS Type of Visual Material (TMat)
008/34 BKS Biography (Biog)
CNR Entry Convention (S/L)
VIS Technique (Tech)
008/38 ALL Modified Record (MRec)
008/39 ALL Cataloging Source (Srce)
038 Record content licensor No plans to implement in WorldCat bibliographic records.
066 subfield ǂa Primary G0 character set No plans to implement in WorldCat bibliographic records.
066 subfield ǂb Primary G1 character set No plans to implement in WorldCat bibliographic records.
760-787 Fill characterfill character ) meaning "No attempt to code"

In MARC 21, the fill character is valid in the defined positions of control subfield ǂ7 in each of the bibliographic Linking Fields. Implementation of the fill character in these WorldCat bibliographic record positions is currently under consideration.

843 subfield ǂ6 Linkage Implementation in WorldCat bibliographic records is under consideration.
845 subfield ǂ6 Linkage Implementation in WorldCat bibliographic records is under consideration.

1.2 Input Standards

OCLC input standards

OCLC has established input standards based on MARC 21 Format for Bibliographic Data, National Level Full and Minimal Requirements, PCC standards, and the advice of OCLC users.

OCLC input standards are defined according to two main levels of completeness:

Level Information
Full Full-level cataloging containing sufficient information to allow the records to be readily used by various institutions worldwide
Minimal Minimal-level cataloging containing only essential information, although additional data may be provided

Input standards for indicators and subfields are in effect only when the field itself is used.

In 2020, OCLC began work to eliminate OCLC-defined codes used in ELvl in favor of those defined by MARC 21. As a result, the former I-level input standard is now the OCLC full-level input standard, and the former K-level input standard is now the OCLC minimal-level input standard.

For input standards for abbreviated-level records, see section 2.4, Full, Minimal, and Abbreviated-Level Cataloging.

Input standards table

The table captioned Input standards for Leader, 008, and 006 elements on the Fixed Field Introduction page contains the input standards for all fixed-field elements as applicable by record format. There is also an Input Standards section on each individual fixed-field element page.

A detailed Input Standards section appears on each variable field page for the field input standards and the subfield input standards. The full-level standard is given first, followed by a slash and the minimal-level standard.

These are the designations used for input standards.

Designation Information
Mandatory Data you must enter to meet the designated standard
Optional Data you decide whether to enter under the designated standard
Required if applicable Data you must enter to meet the designated standard if it is appropriate for the item being cataloged and if the bibliographic information is available
System supplied System-generated data that you cannot change

The following is a schematic of the input standards section at the beginning of each variable field description.

Input Standards

Field (Full/Minimal)
[Full-level standard]/[Minimal-level standard]
1st Indicator  [Name of 1st indicator]
[Value] [Name of value]
2nd Indicator  [Name of 2nd indicator]
[Value] [Name of value]
Subfields (R=Repeatable  NR=Nonrepeatable) Input Standards (Full/Minimal)
ǂ[Code] [Name of subfield] (R or NR) [Full-level standard]/[Minimal-level standard]


The designation (R) identifies a field or subfield as repeatable, which means it may occur more than once. The designation (NR) identifies a field or subfield as nonrepeatable, which means it may occur no more than once. Repeatability of fields or subfields matches MARC 21 specifications.


Some fields, subfields, elements, or values may be marked Obsolete. Do not use. Although some records in WorldCat may still contain this coding, do not use these fields, subfields, elements, or values in current cataloging.

Additionally, some obsolete MARC 21 fields, subfields, elements, or values have been completely removed from WorldCat and are considered invalid. The corresponding descriptive information has been removed from this document. Information concerning invalid fields, subfields, elements, or values can be found in Content designators for bibliographic data, MARC 21 Format for Bibliographic Data, Content designators for holdings data, MARC 21 Format for Holdings Data, and OCLC-MARC Records.

1.3 Bibliographic Formats

There are five MARC 21 data communication formats: Authority, Bibliographic, Classification, Community Information, and Holdings. This manual is based on the MARC 21 Format for Bibliographic Data and MARC 21 Format for Holdings Data and includes information about bibliographic and holdings data. Bibliographic data exist in WorldCat as bibliographic records (BIB) and local bibliographic data (LBD). Detailed holdings data are represented in WorldCat as local holdings records (LHR). The three-character designations are used throughout this document to indicate which record types are valid for individual fields and fixed-field elements.

MARC 21 Format for Bibliographic Data historically had seven bibliographic formats for the different types of materials and modes of issuance: audio-visual materials, books, machine-readable data files, manuscripts, maps, music (scores and sound recordings), and serials. The Bibliographic, Authorities, and Holdings Data formats were formerly known as USMARC. As a result of format integration in the early 1990s, these formats became the single integrated MARC 21 Bibliographic format.

For convenience, OCLC documentation still refers to eight bibliographic formats: Books (BKS), Computer Files (COM), Continuing Resources (CNR), Maps (MAP), Mixed Materials (MIX), Scores (SCO), Sound Recordings (REC), and Visual Materials (VIS). In Connexion, they correspond to the workforms used to create new bibliographic records. In Record Manager, these workforms are known as material type templates. The three-character format designators also serve as search qualifiers.

Choosing a format

Type of Record code (Type) and Bibliographic Level code (BLvl) together characterize the kind of library material represented by the record. You must determine the appropriate Type and BLvl for the material you are cataloging.

The following tables relate the eight bibliographic formats to their respective Type and BLvl codes.

Format Type Name BLvl
Books a Language material a, c, d, m
t Manuscript language material
Computer Files m Computer file a, b, c, d, i, m, s
Continuing Resources a Language material b, i, s
Maps e Cartographic material a, b, c, d, i, m, s
f Manuscript cartographic material a, c, d, m
Mixed Materials p Mixed materials c, d
Scores c Notated music a, b, c, d, i, m, s
d Manuscript notated music a, c, d, m
Sound Recordings i Nonmusical sound recording a, b, c, d, i, m, s
j Musical sound recording
Visual Materials g Projected medium a, b, c, d, i, m, s
k Two-dimensional nonprojectable graphic
r Three-dimensional artifact or naturally occurring object
o Kit

The following is a list of codes for BLvl.

BLvl Name
a Monographic component part
b Serial component part
c Collection
d Subunit
i Integrating resource
m Monograph/Item
s Serial

1.4 WorldCat Bibliographic Records

Bibliographic records

WorldCat uses the concept of a single bibliographic record per language of cataloging to represent a manifestation of a work. Only one WorldCat record should exist in a language of cataloging. For more information on parallel language records, see section 2.6, Language of Cataloging.

When you retrieve records, the system displays a temporary working copy of the WorldCat record. When you modify the copy for local use, the WorldCat record does not retain these modifications. However, you can correct or upgrade and replace the WorldCat record. In this case, the WorldCat record does retain these modifications.

If a WorldCat record does not exist for a manifestation in your language of cataloging, you may create a new record using a workform/template or derive one from an existing record when appropriate.

If a record exists in your language of cataloging for the resource you want to catalog, you may modify the record for local use and add your OCLC symbol to the holdings information.

For more information about editing bibliographic records, see section 5.2, Member Capabilities.

Records are dynamic

WorldCat records may change for reasons that include:

  • Catalogers correct and update WorldCat bibliographic records depending on their Connexion authorization level or Record Manager account role
  • Data may be merged into existing records
  • WorldCat records may occasionally be overlaid by other records, such as full-level Library of Congress (LC) records, Program for Cooperative Cataloging (PCC) records, etc. In these cases, field 040 will contain codes in subfields ǂa and ǂc for the library whose record overlaid the existing WorldCat record. If any fields transfer from the existing record, the codes in its subfields ǂc and ǂd are appended as subfields ǂd to field 040 in the overlaid record.
  • Ongoing quality maintenance such as conversion of obsolete coding and merging of duplicate records
  • Automated maintenance of authorized access points

Derive new records

If you need to catalog a resource and cannot locate an existing bibliographic record in WorldCat, you can derive a new record from a record that has information in common with the resource you want to catalog. For example, use the record from a previous edition as the basis for a new record for a new edition, or use the print record as the basis for a new electronic record.

When you derive the new record, the system transfers selected fields from the existing record to the new one.

Create new records

Workforms/templates contain commonly used fixed-field elements, variable fields, and subfields. Each of the eight bibliographic formats has a specific workform/template. If you do not find an existing or a similar record, you may use a workform/template to enter a new record. Workforms in Connexion are equivalent to material type templates in Record Manager.

When entering bibliographic information in MARC records, apply the most current version of your chosen cataloging instructions. Your choice of cataloging standards should be reflected in the bibliographic record in Desc and/or in field 040 subfield ǂe.

More information

For instructions on how to modify existing MARC records, replace WorldCat records, create new records, and use workforms, see Connexion documentation or Record Manager documentation. For information about correcting existing bibliographic records, see chapter 5, Quality Assurance.

A comprehensive listing of OCLC terms accompanied by definitions can be found in the OCLC glossary.

1.5 Cataloging Documentation

The following is a partial bibliography of various tools and resources available for consultation. Many of these resources are freely available, and some are included in Classification Web Plus, a subscription service available from the Library of Congress.


  • ALA-LC Romanization Tables. Transliteration schemes for non-Roman scripts.
  • Authorities: Format and Indexes. OCLC documentation that provides details on selected topics that catalogers need to identify and verify information in bibliographic and/or authority records available through OCLC interfaces which includes LC Authorities, MeSH, AAT, Canadiana, etc.
  • BIBCO - Monographic Bibliographic Record Cooperative Program. Includes links to the BIBCO Standard Record (BSR) RDA Metadata Application Profile, the BIBCO Participants' Manual, PCC Provider-Neutral E-Resource MARC Records Guide, and PCC Guidelines for Creating Bibliographic Records in Multiple Character Sets.
  • CONSER - Cooperative Online Serials Program. Includes to the CONSER Standard Record (CSR) RDA Metadata Application Profile, CONSER Cataloging Manual (CCM), CONSER Editing Guide (CEG), and other documentation.
  • Library of Congress Standards. Contains links to resource description formats, digital library standards, information resource retrieval protocols, and information resource retrieval standards.
  • MARC Standards. Includes links for all MARC formats, as well as code lists for languages, countries, relators, and many more.
  • Program for Cooperative Cataloging. Provides an overview of BIBCO, CONSER, NACO, and SACO, with links to documentation, information about joining the programs, etc.

Descriptive cataloging

  • Anglo-American Cataloguing Rules, 2nd edition. Available through the RDA Toolkit.
  • Biblioteca Nacional de España (BNE) Authority File. Authority file of the National Library of Spain. Available from within the Record Manager interface.
  • Canadiana Authorities. Canadiana name authority file from Bibliothèque et Archives Canada. Available from within the Record Manager interface.
  • Descriptive Cataloging Manual Section Z1 and LC Guidelines Supplement to the MARC 21 Format for Authority Data. Policy documents for authority records in the Library of Congress authority files.
  • Integrated Authority File (GND). An authority file operated cooperatively by the German National Library, all German-speaking library networks, the German Union Catalogue of Serials and numerous other institutions. Available from within the Record Manager interface.
  • Library of Congress Authorities. Searches Library of Congress name and subject authority files. Available from within Connexion and Record Manager interfaces.
  • Nederlandse Thesaurus van Auteursnamen (NTA Names). The Dutch National Thesaurus for author names from the National Library of the Netherlands. Available from within the Record Manager interface.
  • Resource Description and Access (RDA) Toolkit. Available by subscription from ALA Publishing, it contains RDA, RDA VES Vocabularies, and AACR2. Includes links to various policies that are freely available without a subscription including:
    • Library of Congress-Program for Cooperative Cataloging Policy Statements (LC-PCC PS)
    • Music Library Association Best Practices (MLA BP)


Subject/Genre cataloging

Specialized communities and formats