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6xx Fields

6xx Introduction

6xx fields

Use the 6xx fields to provide subject access entries and terms. Most of the 6xx fields contain subject added entries or access terms based on the authority files or lists identified in the 2nd indicator or in subfield ǂ2. Field 653 contains uncontrolled subject access data.

Input standards

If you are inputting Full-level records, subject added entries are required for items that normally receive subject headings (e.g., nonfiction that is not drama or poetry). If you are inputting Minimal-level records, subject entries are optional, but OCLC encourages you to enter at least one subject heading.

Since fields 690-699 do not remain in the master record, you must input appropriate subject headings in fields 600-651 to meet I-level requirements.

Subject authorities

OCLC defines tags and indicator values for 6xx fields to represent the subject authority of the entry and the agency that assigned the entry. Use the following thesauri or subject heading systems:

  • Library of Congress Subject Headings (LCSH)
  • LC subject headings for children's literature contained in the "AC (Annotated Card) Subject Headings" section of LCSH
  • National Library of Medicine (NLM) authority files
  • National Agricultural Library (NAL) subject authority file
  • Library and Archives Canada (NLC) Canadian Subject Headings
  • Bibliothèque de l'Université de Laval subject headings
  • Sears List of Subject Headings
  • Locally defined thesauri or subject heading systems

Constructing the 600-630 fields

If you are inputting current cataloging, construct entries in fields 600-630 according to Anglo-American Cataloguing Rules, second edition (AACR2) and Library of Congress (LC) practice. Search the OCLC Authority File to verify forms of entry.

Use current LC-AACR2 or AACR2-compatible forms of names and uniform titles. If the current LC-AACR2 or AACR2-compatible form is unknown, construct the heading according to AACR2 and the Library of Congress Rule Interpretations (LCRIs).

If you are inputting retrospective cataloging for fields 600–630, search the OCLC Authority File to verify forms of entry. Use current LC-AACR2 or AACR2-compatible forms of names and uniform titles. If the current LC-AACR2 or AACR2-compatible form is unknown, you may enter the pre-AACR2 form, but you are encouraged to construct the heading according to AACR2 and the LCRIs.

See section 2.2, "Transcribing Pre-AACR2 Copy," for more information.

Constructing the other 6xx fields

For entries in other 6xx fields, use the appropriate thesaurus.

If the topical subject heading is not derived from a standard thesaurus but is compatible with the form of headings from that thesaurus and it has value to institutions other than yours, use either field 650 or field 651 with 2nd indicator 4.

Use field 653 to supplement headings taken from the other thesauri. Field 653 is completely free-text.

If the heading is nonstandard and has meaning only for your institution, use the fields below, which are not retained in master records:

Problematic headings

The Library of Congress has established guidelines for tagging certain corporate bodies and uniform titles. These guidelines and lists of problematic headings are periodically updated and are available in MARC 21, Appendix E - Alphabetical List of Ambiguous Headings. Consult these guidelines when constructing these headings.

Subfields ǂv, ǂx, ǂy and ǂz

In each subject added entry field, OCLC defines subfields ǂv, ǂx, ǂy and ǂz. Use the following guidelines:

  • Treat the word States as a general subdivision (subfield ǂx).
    650   0 Finance, Public ǂz United States ǂx States.
  • Chronological subdivisions qualify a subject in terms of time. You may use dates as a subdivision for this purpose. However, if you use dates to identify a specific occurrence of an event and do not qualify the subject in terms of time, treat the subdivision as a general subdivision (subfield ǂx) instead.
    610 1 0 United States. ǂb Army ǂx History ǂy Civil War, 1861-1865.
    651   0 Oregon (Ill.) ǂx Census, 1990.
  • Treat subdivisions that qualify a subject in terms of the time in which items were written as form subdivisions (subfield ǂv). Chronological subdivisions (subfield ǂy) apply to the subject itself. In the following examples, the first entry applies to items written before 1800 about art of any period. The second entry applies to works about 17th–18th century art whenever written.
    650   0 Art ǂv Early works to 1800.
    650   0 Art ǂx History ǂy 17th-18th centuries.
  • Consider names treated as geographic names (651 or 691) to be geographic subdivisions (subfield ǂz) when they are used as subject subdivisions.
    610 2 0 European Free Trade Association.
    651   0 European Free Trade Association countries.
    650   0 Agriculture ǂx Economic aspects ǂz European Free Trade Association countries.

Subfield ǂ2

If you use subfield ǂ2, enter it as the last subfield in a field. Enter final punctuation if necessary in the subfield that precedes subfield ǂ2.


Usual practice is to spell out all subject entries, however, you should not spell out the following subject entries:

  • Certain names used as parenthetical qualifiers following corporate names
    610 2 0 Population Research Center (U.S.)
  • Abbreviations that are integral parts of corporate names
    610 2 0 U.S. Underseas Cable Corporation.
  • Certain jurisdictional names following geographic place names
    651   0 Houston (Tex.)

See the LC Subject Headings Manual for more information about abbreviations.

Transcription from LC copy

Use the following guidelines when transcribing LC copy:

  • Brackets enclose non-LC subject entries on LC printed cards. The source of the entry is printed at the lower left on the card. If the source is Annotated Card Program Shared Cataloging with DNLM (National Library of Medicine) or Shared Cataloging for DNAL (National Agricultural Library), enter the subject entry without brackets and with the appropriate 2nd indicator value.
  • Do not enter subject entries or portions of subject entries enclosed in brackets except for LC Children's, NLM, or NAL headings.
    Subject Entry on LC Copy Enter
    [Labor supply--Stat.--Russia] Do not enter
    Fruit[--Hardiness] 650   0 Fruit.
  • If LC enclosed a portion of the subject entry in subscript parentheses, enter the data, but do not enter the parentheses.
    Subject Entry on LC Copy Enter
    Wages--(Furniture workers)--United States 650  0 Wages ǂx Furniture workers ǂz United States.
    Spraying and dusting residues (in agriculture) [--Testing] 650  0 Spraying and dusting residues in agriculture.

See section 2.2, "Transcribing Pre-AACR2 Copy" for more information.


The print program selects subject entries for printing in fields 600–651 according to the 2nd indicator and in the other fields according to your profile.

The following subject entries can print:

  • LC (2nd indicator value 0–Library of Congress subject heading)
  • AC Subject Headings (2nd indicator value 1–LC subject heading for children's literature)
  • NLM (2nd indicator value 2–Medical subject heading)
  • NLC (2nd indicator value 5–Canadian subject heading)
  • Bibliothèque de l'Université de Laval (2nd indicator value 6–Répertoire de vedettes-matière)
  • Authority source specified in subfield ǂ2 (2nd indicator value 7–Source is specified in subfield ǂ2)
  • Sears (2nd indicator value 8–Sears subject heading)
  • Locally defined thesauri or subject heading systems

The following subject authorities do not print:

  • NAL (2nd indicator value 3–National Agricultural Library subject heading)
  • Subject headings with authority source not specified (2nd indicator value 4–Source not specified)
  • Uncontrolled subject headings (field 653 [Index Term–Uncontrolled])

For holding libraries profiled for LC, Annotated Card, NLM or Sears, the print program prints the selected subject entries in the following order:

LC Annotated Card NLM Sears
2nd indicator 0

2nd indicator 1

2nd indicator 2

2nd indicator 8
690 690 690 690
691 691 691 691

Local subject entries (fields 690 and 691) print for any holding libraries. Field 695 prints for a holding library based on the library's profile. If field 695 prints in the receiving catalog, fields 650, 651, 690, and 691 do not print. Again, based on the profile, fields 650, 651, 690 and 691 may print in another receiving catalog in the same holding library.

Fields 696-699 do not print.

Printing characteristics

Your profile specifies the following characteristics for each holding library for subject headings:

  • Case (uppercase only, or upper- and lowercase) for subject headings
  • Indention values for subject headings
  • Overprinted or dropped subject headings
  • The card on which the subject tracings print

In headings and tracings, the print program supplies a dash (--) before subfields ǂv, ǂx, ǂy and ǂz.

650   0 Art ǂx History ǂy 17th-18th centuries ǂv Bibliography.
Prints as:

In the tracing paragraph, the print program supplies consecutive Arabic numerals.

This page last revised: April 17, 2019