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670 - Source Data Found (R) - MARC 21 Authority


670 is a field that is used in the MARC 21 authority records to give the Source Data Found from the resource. 670 is a repeatable field, i.e., each source citation is contained in a separate 670 field.

Note: This article chiefly gives information from the Library of Congress MARC 21 documentation on 670.¹


  • Field Definition and Scope
  • Guidelines For Applying Content Designators
    • Indicators
    • Subfield Codes
      • $a - Source citation
      • $b - Information found
      • $u - Uniform Resource Identifier
      • $w - Bibliographic record control number
      • $6 - Linkage
      • $8 - Field link and sequence number
  • Input Conventions
  • Implementation of 670 $w In Proposals


Citation for a consulted source in which information is found related in some manner to the entity represented by the authority record or related entities. May also include the information found in the source.

Each source citation is contained in a separate 670 field.

Citation for a consulted source that yielded no information is contained in field 675 (Source Data Not Found).

Citations and information in this field are often not written in a form adequate for public user display.



Both indicator positions are undefined; each contains a blank (#).

Subfield Codes

$a - Source citation

Citation for a published work or a description of any source or action that provided information about the heading (e.g., a telephone call to a publisher). The citation includes enough information to identify the work, such as the title and imprint date. When a work has a non-distinctive title (e.g., a generic term), the citation may begin with the name of the author. When the author is the same as the 1XX heading, one of the following may be used in the citation: His, Her, Author's (gender unknown), or Its (not a personal name). When a 100 heading is used for more than one person (008/32, Undifferentiated personal name, code b), subfield $a may contain a descriptive term for an author enclosed within brackets (e.g., [Author of Ireland]).

110 2# $a Oxon Hill Manor (Md.)
670 ## $a Phone call to National Register of Historic Places

110 2# $a World Bank
670 ## $a Its Annual report, 1981: $b p.3 (The World Bank is a group of three institutions, the International Bank for Reconstruction and Development (IBRD), the International Development Association (IDA), and the International Finance Corporation (IFC))

100 1# $a Smith, Howard
670 ## $a [Added entry of Inside Japan]
670 ## $a Inside Japan, 1981 (a.e.) $b verso t.p. (Howard Smith)
670 ## $a [Author of Ireland]
670 ## $a His Ireland, 1974: $b t.p. (Howard Smith)

130 #0 $a Headline series
670 ## $a Harsch, Joseph C. Germany at war, 1942: ser. t.p. (Headline books)
[The source cited contains information only concerning a series related to the series being established.]

100 1# $a Breay, Phillis
670 ## $a OCLC, Mar. 1, 2012 $b (hdg.: Breay, Phillis)
675 ## $a The mine explored, 1850
[Name being established was not given in the work cataloged; information found in OCLC WorldCat for the same and/or similar works attributed to Phillis Breay.]

$b - Information found

Parenthetical statement of the information found in the source. A statement of the location of the information within the source, such as cover, t.p., foreword, may also be contained in subfield $b. Multiple occurrences of location/information found within the same source are contained in a single subfield $b.

100 1# $a Defoe, Daniel, $d1661?-1731
670 ## $a InU/Wing STC files $b (usage: a lay-hand in the country)

110 2# $a Twin City Federal
670 ## $a Lund, D. A. Billions for homes, c1980 (subj.) $b t.p. (TCF) verso t.p. (Twin City Federal) p. 11 (founded 4-2-23)

110 2# $a Bentley Historical Library
670 ## $a Billington, R. A.$bLocal history is ... 1974.
670 ## $a Its Guide to manuscripts in the Bentley Historical Library, 1976: $b t.p. (Bentley Historical Library, Michigan Historical Collections, Univ. of Mich.)

130 #0 $a Astronomy library
670 ## $a Eicher, D.J. Beyond the solar system, c1992: $b t.p. (Astronomy library)

$u - Uniform Resource Identifier

Uniform Resource Identifier (URI), for example a URL or URN, which provides electronic access data in a standard syntax. This data can be used for automated access to an electronic item using one of the Internet protocols.

100 1# $a King, Stephen, $d 1947-
670 ## $a The official Stephen King web presence, viewed Oct. 26, 2001: $b The man (Stephen Edwin King; b. Portland, Maine, 1947) $u

$w - Bibliographic record control number

System control number of the related record preceded by the MARC code, enclosed in parentheses, for the agency to which the control number applies.

150 ## $a Dunking (Basketball)
670 ## $a Work cat: Year of the dunk, 2015 $w(DLC)2014041716

150 ## $a Cabala
670 ## $a Bloom, H. Kabbalah and criticism, c1975 $w(DLC)75012820 $w(OCoLC)1339798

100 1# $a Snyder, G. Irvin
670 ## $a Our soldier boys in khaki o'er in France, ©1918: $b t.p. (G. Irvin Snyder) $w(DLC)2014561136 $w(OCoLC)899258216

$6 - Linkage

See description of this subfield in Appendix A: Control Subfields.

$8 - Field link and sequence number

See description of this subfield in Appendix A: Control Subfields.


Punctuation and Spacing - Punctuation and spacing is a matter of judgment. The examples used in the Guidelines area reflect current Library of Congress practice.

Order - First 670 field in a record should contain the citation for the work for which the 1XX heading is being established whenever there is one. Other sources may be listed in any order.


Implementing 670 $w - A Presentation for PCC At Large - ALA Midwinter Meeting 2020 - by Janis L. Young, Policy, Training, and Cooperative Programs, Library of Congress.²

Current Practice

LCCNs appear in subfield $a of “Work cat.” citations in authority records

670 ## $a Work cat.: 2015300502: Finding Julia, 2014: $b p. 13 (Bollinger family) …

New Practice

LCCNs will appear in subfield $w of “Work cat.” citations in authority records

670 ## $a Work cat.: Finding Julia, 2014: $b p. 13 (Bollinger family) … $w (DLC)2015300502

Impacted Vocabularies
  • LC subject headings
  • LC genre/form terms
  • LC medium of performance terms for music
  • LC demographic group terms
    • Moratorium on proposals

Impacted Citations

  • “Work cat.” citations in proposals for new headings
  • New “Work cat.” citations in proposals to revise existing records
    • Do not revise existing citations to append $w

Which Control Numbers?
  • LCCNs 
    • LC proposals
    • SACO proposals made for CIPs cataloged in the CIP Partnership Program
  • Other bibliographic record control number
    • May be provided by SACO members
      • Not mandatory
  • Local control number
  • Bibliographic utility control number

Format of Subfield $w
  • One subfield $w per citation
    • Appears as the final subfield of 670 field
  • Preceded by the MARC code for the agency to which the number applies, enclosed in parentheses

$w (DLC)2020123456
$w (OCoLC)198765401

Anticipated Timeline

  • February 2020
    • Documentation
      • Subject Headings Manual 
      • Draft genre/form, medium of performance, and demographic group terms manuals
  • Proposal templates
  • Use of 670 $w in proposals begins
    • PTCP will correct coding of LCCNs in proposals
  • April 2020 (no earlier than)
    • 670 $w appears in approved authority records
    • PTCP will begin returning miscoded proposals to catalogers for correction before the proposal is scheduled for a tentative list



1. Library of Congress, "670 - Source Data Found (R)," (accessed February 27, 2020).

2. Library of Congress, "Implementation of 670 $w in Proposals (Janis L. Young, Library of Congress)" (accessed February 27, 2020).


Article Title
  • 670 - Source Data Found (R) - MARC 21 Authority

Website Name
  • Librarianship Studies & Information Technology


Last Updated
  • 2020-02-27

Original Published Date
  • 2020-02-27

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