In 1983, OCLC established the Enhance function in an effort to decentralize quality control responsibility for WorldCat. Until that time, most quality control activity was centered in what is now known as WorldCat Metadata Quality at OCLC. The sole exception to this had been the CONSER Program, the mechanism for updating and correcting serial records.

Until the implementation of Enhance, the only mechanism for changes to non-serial records was reporting by paper change requests or submitting a change request to OCLC via any of the available electronic means. OCLC staff could make corrections using Master Mode authorizations. The initial group of 20 libraries was invited to join the Enhance program in May 1984.

Late in 1985, responsibility for WorldCat quality control was further decentralized with the implementation of the Minimal-Level Upgrade capability. This allowed cataloging full mode authorizations and higher to lock, edit, and replace Encoding Levels K, 7, and (in 1987) M records. In the early years of Enhance, libraries were chosen through a series of application rounds or as special projects. In September 1989, the Regular Enhance application process was opened year-round, regardless of bibliographic format. At the same time, OCLC ceased face-to-face training of Enhance libraries in favor of using the Enhance Training Outline as the major instructional tool.

In 1991, the Database Enrichment capability was implemented, allowing full mode and higher authorizations to add subject headings and call numbers to records. The ability to add 505 contents notes became part of Database Enrichment in August 1992. Also in 1992, it became possible for full and higher authorizations to add 300 physical description fields to CIP records. Allowing Enhance participants to upgrade any CIP record, except for its Encoding Level value of 8, was introduced in 1993.

National Level Enhance became a reality in September 1994. This allowed selected Library of Congress (LC) cataloging staff and Program for Cooperative Cataloging (PCC) participants to lock, edit, and replace any record with an Encoding Level of blank, 1, or 8. National Level Enhance authorizations were granted by invitation only, in consultation with the Library of Congress.

Database Enrichment was further expanded in March 1996 when fields 006 and 007 were added, and yet again in August 2002 with the addition of over two dozen 0xx, 5xx, and 6xx fields.

The Expert Community is an expansion of master record editing capabilities to all full level cataloging users. It was tested as the Expert Community Experiment in 2009. The Experiment resulted in more corrections and additions to master bibliographic records and more timely actions to correct record problems. The Experiment was inspired by longstanding requests from members of the OCLC cooperative to be able to do more—and more immediate—upgrading of bibliographic records in WorldCat. The Experiment allowed us to test a "social cataloging" model involving the existing community of cataloging experts who have built WorldCat record-by-record. Interest in such a model grew especially with the launch of WorldCat Local and with the popularity of such other socially cooperative ventures as Wikipedia.

At the end of the experiment later in 2009, the expanded capabilities were permanently added to the full level authorization. OCLC's Expert Community provides Connexion users who have a full level authorization or higher more flexibility in making changes to WorldCat master bibliographic records. Maintenance of WorldCat is shared more equally between OCLC staff and member libraries. The additional capabilities provided are a powerful expansion of those that have been available especially through Database Enrichment since 1991.

The Library of Congress along with bibliographic utilities and other national library cooperative programs created the Cooperative Cataloging Council in November 1992. This Council created the Program for Cooperative Cataloging in February 1995. The following programs are components of the PCC:

BIBCO for bibliographic record input

BIBCO participants contribute bibliographic records to international databases, meeting or exceeding the elements of the BIBCO Standard Record. BIBCO records include headings backed by complete authority work, both descriptive and subject. The BIBCO core level record standard is provided for reference, but has been retired as a standard for PCC BIBCO records. In 2010, the BIBCO program replaced its “full” and “core” record standards by the single encoding level: BIBCO Standard Record (BSR). The BSR for Textual monographs was implemented on January 1, 2010, and BSRs for other types of materials were implemented October 1, 2010.

CONSER for master serial records

CONSER began in the early 1970s as a project to convert manual serial cataloging into machine-readable records and has evolved into an ongoing program to create and maintain high quality bibliographic records for serials. In keeping with its evolution, the name was changed in 1986 from the CONSER (CONversion of SERials) Project to the CONSER (Cooperative ONline SERials) Program. In October 1997, CONSER became a bibliographic component of the Program for Cooperative Cataloging. The CONSER database resides within WorldCat. CONSER members input, authenticate, and modify serial cataloging records in WorldCat. Authentication is the process of approving the bibliographic elements in the record and providing for the record's availability through distribution services and bibliographic products.

NACO for name authority input

The Name Authority Cooperative Project (NACO) was established in 1977 as a result of an agreement between the Library of Congress (LC) and the U.S. Government Printing Office (GPO) to use and maintain a common authority file. With the success of this initial project, LC entered into additional cooperative cataloging projects with many other institutions. The partners in cooperative cataloging efforts eventually developed the Program for Cooperative Cataloging (PCC) to administer these projects, including the Subject Authority Cooperative Program (SACO), the Bibliographic Cooperative Program (BIBCO), and the Cooperative Online Serials Program (CONSER).

SACO for subject authority input

SACO was established to provide a means for libraries to propose new Library of Congress Subject Headings (LCSH) and LC Classification (LCC) numbers. It also allows libraries to submit change proposals for existing subject headings and classification. In 2010, SACO became an institutional membership-based program of the PCC. At that time, current members of any of the other PCC programs were automatically considered to be SACO members. Since 2010, new PCC members interested in participating in the SACO Program are required to submit a SACO application.

For information about the goals of the PCC and/or participating, see the Program for Cooperative Cataloging (PCC).

OCLC first developed the capability to merge bibliographic records manually in 1983. During the late 1980s and early 1990s, OCLC developed automated Duplicate Detection and Resolution (DDR) software. The original DDR dealt with books format records only. Between 1991 and 2005, DDR merged 1,592,586 book records.

OCLC began working on a replacement to the old DDR software in 2005, when the transition from the PRISM system to the Connexion system meant that the old DDR would no longer be usable. After four years of rigorous planning, careful development, and extensive testing, OCLC put the new software into limited production in May 2009, processing small targeted subsets of WorldCat. Between May 2009 and January 2010, OCLC processed about 500,000 records in this way. The result was the merge of roughly 15,000 duplicates, every one of which was examined individually. Something was learned from every incorrect merge. Records were pulled apart, and the sofware fine-tuned so that a particular problem would not occur again. One significant difference between the old and new versions of DDR is that the new one works on records in all bibliographic formats, not just books.

Between May 2009 and September 2011, the DDR software made one complete cycle through all of WorldCat, processing over 166 million bibliographic records, resulting in the deletion of 5,126,132 duplicates. DDR has been running since then on a daily basis, processing new and specially selected records that have been updated. For the most up-to-date statistics of the number of duplicates being deleted by DDR, visit OCLC delivers quality.

Responsibility for metadata quality in WorldCat bibliographic database is decentralized allowing members to modify existing master records. Members can correct or revise a working copy of a master record and then replace the master record with the edited version.

In addition to replacing records created by your own institution, you can also replace non-PCC records and non-CONSER authenticated continuing resource records.

If you notice errors or omissions after you input a master record, you can correct them and replace the record, provided it has not been edited to become a PCC or CONSER-authenticated record.

This table shows the different authorization levels and their relationship to replacing records using Connexion.

For more detailed information including the different authorization level capabilities between the Connexion client and browser interfaces, see OCLC Cataloging Authorization Levels for Record Actions and Upgrades.

This table shows the authorizations, now known as account roles, and their relationship to replacing records using WorldShare Record Manager.

For more detailed information about Record Manager account roles, see Record Manager account roles.

Just as you follow applicable cataloging instructions when adding records to the WorldCat bibliographic database, follow the same standards when modifying data in any master record, whether created by your institution or by other members.

Use the following guidelines:

• Do not alter a record to represent a different bibliographic entity even if the record has no holdings or only your holdings attached. If you are in doubt about whether your item matches the record, do not upgrade the record. Edit it for local use, or, if appropriate, input a new record.
• Do not assume that your information is correct and the existing record is incorrect if your cataloging differs. If in doubt, report errors.
• Do not change records from one language of cataloging to another. See section 3.10 Parallel Records for Language of Cataloging.
• Do not add descriptive elements in your language of cataloging to a record cataloged in a different language (e.g., do not add English descriptive elements to a French cataloged record).
• Verify the appropriate data elements are present for the encoding level specified for the record. Check tagging, subfield indicators, and coding.
• Verify name access points in the authority file appropriate for the language of cataloging. Name access points must be in the appropriate form.
• You may replace a record after controlling the access points even if no text has changed. Verify that access points were controlled as expected before replacing the record.
• Use current subject terminology whether the record is original cataloging or is being upgraded. Verify subject access points in the authority file appropriate for the language of cataloging.
• Do not replace a record solely to change elements that are a result of judgment (e.g., a choice of entry or call numbers).
• Do not delete data entered by another library unless it is incorrect in substance. For example, you may delete a subject access point that does not apply.
• Do not delete call numbers and subject access points not used in your library.
• Do not add local information to a master record.
• You are not required to verify call numbers or subject access points in a scheme that your library does not use.

In all records, you can locally edit Type and BLvl.

Full-level or higher authorization:

• You can change Type and BLvl in minimal-level records (ELvl coded 2, 3, 4 (without field 042 pcc), 5, K, M).
• You can change Type and BLvl in full-level records you input where your holding symbol is set and there are no other holdings.
• You cannot change Type and BLvl in full-level records (ELvl coded , 1, 4 (with field 042 pcc), I) or CONSER-authenticated continuing resources, unless the bibliographic format remains the same (e.g., Type: i can be changed to Type: j).

With Full-level cataloging authorization or higher, you can upgrade records to become full-level records, or you may upgrade abbreviated and partial level records to minimal-level or full-level records.

Encoding level 8. Prepublication level records, including Cataloging in Publication (CIP) records. Participants cannot change the Encoding Level as they can for other records. Do not edit fields 010, 040, national call number fields, or field 263 in CIP records.

Catalogers with replace capabilities can enrich Program for Cooperative Cataloging (PCC) master records, except CONSER-authenticated continuing resource records, by adding or editing the fields in the table below. A full-level record has one of these values in ELvl (Encoding Level): , 1, 4 (with field 042 coded pcc), or I). The various conditions for adding these fields are given after the table below.

It may be beneficial to complete edits is one session, editing PCC records should always be done in one session.

Fields you can add or edit on non-CONSER PCC records

Multiple call numbers

Certain classification choices are local decisions. Multiple call numbers in the master record may be appropriate in these circumstances:

• Classed together vs. classed separately call numbers for items in monographic series
• PA-PT vs. PZ numbers for classification of fiction
• Bibliography classification vs. subject classification
• LC minimal number vs. member call number
• Geographic classification vs. subject classification for maps and atlases

Full-level users can add or change non-Latin script fields in full-level master records. There can be more than one non-Latin script in a single field and/or a single record. Most 1xx-8xx fields and some 0xx fields can have non-Latin script equivalent 880 fields. For a list of fields which can contain non-Latin script data see Control Subfields, subfield ǂ6.

You can add local information (defined in the table below) as part of the editing that you do before replacing the record. The local information is not added to the master record as part of the replace transaction, but it is retained in your working copy of the record. If you complete editing before replacing the record you can add your holdings immediately after completing the replace transaction.

When you lock a record, other users can display it and use it for cataloging, but no one else can lock or replace it. If you attempt to lock a record that is already locked, the system responds with a message that the record is locked by another user. To increase efficiency, OCLC recommends that you edit and replace locked records as quickly as possible.

The system automatically releases locked records in the following cases:

• System or communications failure while a locked record is displayed. Such records remain locked until your session has timed out.
• Inactivity log off while a locked record is displayed
• A locked record in the online save file more than 14 days
• A locked record is deleted from the online save file

With Full-level cataloging authorization or higher, you can close-out, link, edit, and/or correct full-level non-CONSER continuing resource records. You cannot enhance or maintain continuing resource records authenticated by CONSER.

CONSER-authenticated records have one of the following codes in field 042:

See section 5.3 Program for Cooperative Cataloging for more information.

The Program for Cooperative Cataloging (PCC) seeks to increase participation in national programs by lowering participants' cost without lowering cataloging standards and quality. You may be eligible to participate in cooperative programs to improve the quality of WorldCat through the PCC. OCLC provides authorizations to participate in PCC programs. For information about the goals of the PCC, see the PCC website.

The Bibliographic Record Cooperative (BIBCO) program provides for the upgrade and replacement of master bibliographic records. OCLC provides authorizations to participate in BIBCO. Users that have BIBCO capabilities can edit records with PCC coded in field 042 and can also change the Encoding Level for 8 (Prepublication-level CIP) Books format records; however, BIBCO participants cannot edit CONSER authenticated continuing resource records. If you are interested in BIBCO participation, see the BIBCO website.

The Cooperative Online Serials (CONSER) program provides for the upgrade and replacement of master bibliographic continuing resouce records. OCLC provides authorizations to participate in CONSER. Users that have CONSER capabilities can edit continuing resources records with one of the CONSER codes in field 042. If you are interested in CONSER participation, see the CONSER website.

The Name Authority Cooperative (NACO) program allows participants to contribute authority records for agents, places, works, and expressions to the LC/NACO Authority File. OCLC provides authorizations to participate in NACO. Users that have NACO capabilities can add and edit name authority records (NARs) and series authority records (SARs) in the LC/NACO Authority File. NACO participants can also participate in the Subject Authority Cooperative (SACO) program. OCLC does not provide authorizations to participate in SACO but NACO libraries are able to submit proposals for additions to the Library of Congress Subject Headings (LCSH), LC Genre/Form Terms (LCGFT), LC Demographic Group Terms (LCDGT), LC Medium of Performance Thesaurus for Music (LCMPT), and LC Classification (LCC) schedules. If you are interested in NACO participation, see the NACO website. If you are interested in SACO participation, see the SACO website.

BIBCO and CONSER participants have the following capabilities:

• National enhance (BIBCO) authorization: You can change Type and BLvl in the formats for which you are authorized as long as the bibliographic format stays the same.
• CONSER authorization: You can change Type as long as BLvl is already coded i or s. You can edit records in any format where BLvl i or s is valid. For more information on CONSER editing capabilities, see the CONSER Editing Guide.

BIBCO and CONSER participants cannot:

• Add, change, or delete field 019
• Add, change, or delete field 029
• Add, change, or delete field 938
• Change field 040 subfield ǂc and subfield ǂd
• Delete a master record from WorldCat

Metadata Quality at OCLC is responsible for data quality within the WorldCat bibliographic database, knowledge base, and registry. Staff responsible for quality within the WorldCat bibliographic database works with bibliographic and authority records, and merges duplicate bibliographic records. The staff also provides feedback and analysis to OCLC data programs and services. For more information, see OCLC delivers quality.

Duplicate Detection and Resolution (DDR) software processes bibliographic WorldCat records to identify and merge duplicates. WorldCat Metadata Quality staff also identifies and manually merges duplicate records. Staff is trained to merge in specialized formats.

To learn more about how to determine whether an existing record matches the resource you are cataloging or whether you should input a new record, see chapter 4, When to Input a New Record.

You can report bibliographic duplicate records to the WorldCat Metadata Quality staff. For more information, see section 5.5 Requesting changes to records for more information.

As NACO participants, staff creates or modifies name authority records in the LC/NACO name authority file. Staff manually resolves name authority conflicts and revises authorized access points in accordance with RDA. Requests to change name authority records from other authority files will be forwarded to the agency that manages those files.

In addition to DDR, large sets of bibliographic records may be modified to reflect current policy thru the use of automated tools. Changes or updates are done on large sets of records through the use of automated tools. OCLC has updated records in WorldCat to incorporate RDA elements such as adding 33x fields, spelling out non-transcribed abbreviations, converting Latin abbreviations to English equivalents, converting dissertation notes in field 502 to multiple subfields, and removing the general material designation (GMD).

OCLC adds various symbols when updating, changing, or generating bibliographic records:

You may find a master record that does not comply with cataloging instructions or OCLC standards. In most cases, you can replace the record to enrich it, upgrade it, or correct errors. In all other cases, you should report errors or omissions to OCLC. See section 5.2 Member Capabilities for more information on replacing records.

You can also correct and modify a retrieved master record for local use and export the record. Do not replace the master record if your changes are the result of cataloger judgment or local policy. Do not report such changes as errors. Alternatively, you may create local bibliographic data records to accomodate local information.

If you are unable to replace the master record, OCLC encourages you to report:

• Duplicate records and incorrect merges
• Type and BLvl code changes
• Non-filing indicator changes
• Correction of name access points
• Inappropriate subject access points
• Other changes, corrections, and additions to bibliographic records that the system will not allow you to change

Non-NACO libraries can submit corrections to existing authority records and request the creation of an authority record. Send authority record requests to authfile@oclc.org.

Requests for bibliographic file maintenance can be submitted to Metadata Quality staff at bibchange@oclc.org.

Final disposition of reports is at OCLC's discretion. OCLC may return reports to the reporting library for clarification or forward the reports to the inputting library or other holding libraries for verification.

Libraries that are unable to replace master records can report them to OCLC for correction.

Proof is essential for changes unless there are obvious MARC coding errors, such as subfield codes missing from field 245, tags for fields 260 and 300 are reversed, or a personal name tagged as a corporate body. Title page and publication information, including typographical idiosyncrasies, are taken directly from the item. OCLC often refers questions to the creator of the record and is conservative when evaluating change requests.

The justification for changing a record is the same as that needed to catalog the item originally. In some cases, the justification for a requested change may be any standard classification, descriptive, or subject cataloging manual. When necessary, provide the appropriate guideline or instruction number.

Proving a change is valid includes verifying that the item in hand is the exact item described in the bibliographic record. If proof from the item is required, send clearly labeled images and any pertinent URLs with the error report. Label the pages as:

• Title page
• Title page verso
• Cover, spine, etc., if change involves these areas
• Publication information pages
• Other pages from the item depending on the request, e.g., bibliography pages differ on the item from what is on the bibliographic record

Proof not required:

Proof may be required:

OCLC encourages members to replace the master record to enrich it, upgrade it, or correct errors. See section 5.2 Member Capabilities for more information on replacing master records.

Do not report the following:

• Changes that would, in effect, recatalog the entire record to different cataloging instructions (adding ISBD punctuation to a non-ISBD record or changing the choice of access points)
• Changes to classification numbers caused by revision of classification schedules
• Information needed only to complete field 300 in CIP records
• Insignificant variations in punctuation, capitalization, and abbreviation, including final punctuation in any field or spacing in field 300
• Use of "Basic" coding option or "Enhanced" coding option in field 505

You may request the deletion of bibliographic records for the following categories:

• Locally produced materials such as video recordings
• Records with no holdings (usually requested by the contributing library)
• Special projects/special circumstances, e.g., member library submits vendor records they purchased but did not have the rights to share the records with WorldCat
• Records involving legal matters
• Request indicating the resource was never published

To determine whether two or more serial records should be represented by one record, apply LC-PCC PSs for RDA 1.6.2 and the LCRIs for AACR2 21.2-21.3.

Request the consolidation of serials by reporting these records to OCLC. OCLC may forward the request involving CONSER-authenticated records to LC. OCLC uses the following criteria when considering requests:

• At least one record must be an RDA or AACR2 record
• Proof must be sent so that variations can be clearly identified (e.g., title, frequency, publisher, and place of publication)
• OCLC normally chooses the record with the earliest coverage dates as the single record to represent the entire run
• When requesting a consolidation, give details of the changes necessary to make the record represent the entire run
• Linked CONSER records and linked records with different ISSNs may reflect valid past practice for treatment of changes in titles and are often not candidates for consolidation

You may use the following reporting methods:

• Report errors online:
• • Connexion client: Take Actions on Bibliographic Records
  • Connexion browser: ​Edit Bibliographic Records
  • Record Manager: OCLC WorldShare Metadata Record Manager User Guide
• Email bibliographic record requests to: bibchange@oclc.org
• Email authority record requests to: authfile@oclc.org
• Complete the WorldCat and Authority Record Quality Control Request form and then:
• • Submit the form online or
  • Fax requests toll-free to: 1-866-709-6252 (US and Canada only) or
  • Mail paper change requests to:
    OCLC
    WorldCat Metadata Quality MC139
    6565 Kilgour Place
    Dublin, OH 43017-3395

More esoteric questions or requests for advice on cataloging policies, standards, and practices should be sent to askqc@oclc.org.