Contents   Fixed field   Access points   0xx   1xx   2xx   3xx   4xx   5xx   6xx   7xx   8xx   9xx   Control subfields

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 information in machine-readable cataloging records in the WorldCat database. It provides tagging conventions, input standards, and guidelines for entering information.

WorldCat is a database of bibliographic records that are descriptions of items held by or accessible to OCLC member institutions. The system links bibliographic records, location information, holdings information, and authority data.

When working online, catalogers either create original bibliographic records if no cataloging copy is found or edit existing records as part of copy cataloging. For both original and copy cataloging, catalogers can add their OCLC symbol to indicate their institution holds or has access to the item.

Members catalog library materials according to current recognized cataloging standards such as Resource Description & Access (RDA) and Anglo-American Cataloguing Rules, 2nd edition (AACR2). Members may also enter older cataloging copy during retrospective conversion. They can catalog all types of library materials in languages that use Latin and non-Latin scripts.

Members may enter records according to Dublin Core (DC) practices. These records will not conform to RDA or AACR2.

1.1  MARC Bibliographic Records


The MARC standard 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).

The MARC record consists of three parts:

  • Leader: Data elements that contain coded values based on their position, which define the processing of the record. It is fixed in length (24 positions) and is found at the beginning of the 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: The data content is divided into variable control fields (no indicators) and variable data fields. OCLC requires that each record have at minimum one variable data field (field 245 with either a subfield ǂa or subfield ǂk) in addition to the necessary control fields (LDR and 008). Inclusion of all other fields is dependent on the item being cataloged.

In OCLC cataloging interfaces the Leader and the 005 and 008 variable control fields are displayed as a single area with mnemonic labels for each element, called the fixed field. Users have the option to display the fixed field as separate fields in Connexion client and WorldShare Record Manager.

The variable control fields (005, 006, 007, 008) do not have indicators or subfield codes. OCLC uses subfield codes in 007 field displays to assist with readability and editing. The subfield codes are not included in electronic versions of the record.

Variable data fields will vary in number, and in length. Each variable field can have between 1 and 9,999 characters. They are identified by the following information:

  • Tag: a 3-digit numeric value coded 010 through 999
  • Indicators: 2 positions, coded with blank or 0 through 9 as possible values
  • Subfields: A textual element identified by a delimiter and a lowercase alphabetic or numeric code

These parts identify how data is indexed and displayed in WorldCat.


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 data elements have not been implemented by OCLC. For a list of these elements, see MARC 21 Bibliographic Data Elements not Implemented by OCLC.


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

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


In MARC records, indicators supply information about the field for indexing, display, or other system functions. Numbers in the indicator positions have assigned meanings and in some fields, a blank is meaningful. Variable field indicators may have:

  • A number in both positions
  • A number in one position and a blank in the other
  • Two blanks


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 the Connexion Client the subfield delimiter displays as a double dagger, while in other OCLC cataloging interfaces the subfield delimiter displays as a dollar sign.

Subfields usually contain the textual information for the bibliographic description of the item. In other cases they contain coded information. Subfield ǂa is implicit at the beginning of each field, and the subfield code does not display. However, subfield ǂa does display when it is preceded by another subfield.

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 levels of completeness:

Level Information
Full Full-level cataloging containing sufficient cataloging information to allow the records to be readily used by various institutions worldwide
Minimal Minimal-level cataloging containing only essential cataloging 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.

Input standards table

A table identifies full-level and minimal-level input standards at the beginning of the fixed-field elements section and at the beginning of each variable field description. The full-level standard is given first, followed by a slash and the minimal-level standard.

The following designations are used in the input standards table at the beginning of each variable field description. They also appear in an abbreviated form in the table at the beginning of the fixed-field elements section:

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 characters appear in the Input standards tables:

Character Information
blank character Blank, distinguished from a fill character and used when a blank is significant
fill character Fill character, distinguished from a blank

The following is a schematic of the input standards table 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[Subfield 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.

  • A repeatable field may occur more than once in a record.
  • A repeatable subfield may occur more than once in a field.

The designation (NR) identifies a field or subfield as nonrepeatable, which means it may occur no more than once. Fields or subfields are nonrepeatable for a variety of reasons:

  • The data element may occur no more than once for a given item.
  • The data element may occur more than once, but you enter multiple data elements in the same subfield.
  • The data element may occur more than once, but you enter multiple data elements in separate fields.

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 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, element, or values can be found in OCLC-MARC Records.

1.3  Bibliographic Formats


There are five MARC 21 data communication formats: Authority, Bibliographic, Classification, Community Information, and Holdings. This document 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, formerly known as USMARC, 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. As a result of Format Integration in the early 1990s, these formats became the single integrated MARC 21 Bibliographic format, but in many contexts, they remain convenient shorthand.

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 OCLC Connexion, they correspond to the workforms used to create new bibliographic records. In WorldShare 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 to represent a manifestation. Only one WorldCat record is allowed per manifestation per 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. You can also correct, enhance, or upgrade the WorldCat record. In this case, the WorldCat record does retain these modifications.

If a WorldCat record does not exist for a manifestation, you may create a new record using a workform/template or derive one from an existing record.

Existing records

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

Records are dynamic

WorldCat records often change because:

  • Catalogers with full-level authorizations can change most WorldCat records
  • In automated record loading:
    • Data may be merged into existing records
    • WorldCat records may occasionally be overlaid by other records, such as full-level LC records, 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

Derive new records

If you retrieve a record that has information in common with the item you want to catalog, you may use that record as the basis for the new record. 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 formats has a specific workform. If you do not find an existing or a similar record, you may use a workform to input a record. Workforms in Connexion are equivalent to material type templates in WorldShare Record Manager.

When entering bibliographic information in MARC records, apply the most current version of your chosen cataloging guidelines. Your choice of cataloging standards should be reflected in the bibliographic record, in either Desc 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 WorldShare Record Manager documentation.

1.5  Cataloging Documentation


The following is a partial bibliography of the various tools and resources available for consultation. Many of these resources are included in the Cataloger's Desktop, a subscription service available from the Library of Congress. Others may be accessed free of charge.


  • ALA-LC Romanization tables
  • Authorities: Format and Indexes
  • BIBCO Documentation. Includes links to the PCC RDA BIBCO Standard Record, the BIBCO Participant's Manual, PCC Provider-Neutral E-Resource MARC Records Guidelines, and PCC Guidelines for Creating Bibliographic Records in Multiple Character Sets.
  • CONSER Documentation. Includes a link to the CONSER Standard Record Documentation. The CONSER Editing Guide and the CONSER Cataloging Manual are available only through Cataloger's Desktop.
  • 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, and much more.
  • Standards at the Library of Congress. Contains links to resource description formats, digital library standards, information resource retrieval protocols, ISO standards, and other standards of interest.

Descriptive cataloging

  • Anglo-American Cataloguing Rules, 2nd edition. No longer available as a stand-alone print document, it is available through Cataloger's Desktop and the RDA Toolkit.
  • LC-NACO Name Authority File, available from within OCLC cataloging interfaces.
  • Resource Description and Access (RDA) Toolkit. Includes links to various tools that are freely available without a subscription (click Resources tab) including:
    • Library of Congress-Program for Cooperative Cataloging Policy Statements (LC-PCC PS)
    • Music Library Association Best Practices


Subject/Genre cataloging

Specialized communities and formats

This page last revised: August 29, 2020