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DATE: December 19, 2008


NAME: Adding subfield $u for Uniform Resource Identifier to field 510 (Citation/References note) of the MARC 21 Bibliographic Format

SOURCE: Bibliographic Standards Committee, ALA/ACRL/Rare Books and Manuscripts Section

SUMMARY: This paper proposes adding subfield $u (Uniform Resource Identifier) to the field 510 (Citation/References note) of the MARC 21 Bibliographic Format in order to provide an active link and immediate online access to a full description of the bibliography cited.

KEYWORDS: Field 510 (BD); Subfield $u, in field 510 (BD); Uniform Resource Identifier (BD); Citation/References note (BD)



12/19/08 - Made available to the MARC 21 community for discussion.

01/25/2009 - Results of the MARC Advisory Committee discussion - Approved with the understanding that there would be some more examples that are not rare books and some instructions about positioning added.

02/17/2009 - Results of LC/LAC/BL review - Agreed with the MARBI decision.

Proposal 2009-05: Adding subfield $u in field 510


The MARC Advisory Committee has in recent years approved the addition of subfield $u (URI) for a number of fields. These include in particular note fields, such as 505, 520, 545, etc. In each case, the addition of subfield $u (URI) has resulted in facilitating user access to online information that is more current, and easily maintained outside of the MARC record.

Field 510 in the MARC 21 Bibliographic Format is used in a number of different ways to specify where an item has been cited or reviewed.  These include references to published descriptions of the resource (books, music, unpublished visual materials), references to reviews, abstracts, or other descriptive information (unpublished visual materials and mixed materials), and indexing and/or abstracting coverage (continuing resources).


2.1 Current use of field 510

Field 510 is used extensively in the description of rare materials. These materials are the subject of significant scholarly bibliographic study, and significant bodies of materials have been described in great detail in published bibliographic works. The inclusion of a citation to such a published description in the MARC21 bibliographic record describing a rare item allows a user of that record to obtain additional detailed descriptive information about the item. The common practice is to use succinct citations in 510 $a as specified in the publication Standard Citation Forms. These citations provide a standardized vocabulary for this element, but the abbreviated forms are not always familiar to users.

Field 510 is currently defined in the MARC 21 Format for Bibliographic Data as follows:

510 Citation/References Note (R)


First - Coverage/location in source
      0 – Coverage unknown
      1 – Coverage complete
      2 – Coverage is selective
      3 – Location in source not given
      4 – Location in source given

Second - Undefined
      # - Undefined

Subfield Codes

      $a – Name of source (NR)
      $b – Coverage of source (NR)
      $c – Location within source (NR)
      $x – International Standard Serial Number (NR)
      $3 – Materials specified (NR)
      $6 - Linkage (NR)
      $8 - Field link and sequence number (R) 

2.2 Adding subfield $u to field 510  (Citation/References note)

Descriptions of standard bibliographies (not to mention of other published material) has become increasingly available online through persistent identifiers such as the LCCN Permalink, which links to LC records using persistent URIs. Inclusion of such identifiers in the reference note (510) would provide an active link to a full description of the bibliography cited.  An example of this is given below.

Furthermore, some of the most significant bibliographic works – the English Short-Title Catalogue is the most obvious example – are themselves available online and provide persistent identifiers to the descriptions of individual items.  The inclusion of these identifiers in the reference note would allow users immediate online access to the referenced description.  Two examples of this are given below.

A new subfield $u in field 510, would be appropriate for this information, since using field 856 creates the user expectation that there is a link to the full text of the resource described, not to a description of the resource.

Although the motivation and background for this proposal relates to the use of field 510 for references to published descriptions of rare materials, the increased availability of persistent identifiers and of online tools are applicable to the other uses of field 510.  It might be possible, for example, to use 510 $u to provide a link to an abstracting/indexing database.


In field 510 (Citation/References note) of the MARC 21 Bibliographic Format:


1. Persistent identifier for the record for the resource cited:

  245 03  $a An abstract of the remarkable passages in the life of a 
          private gentleman. 
  250 ##  $a 4th ed. 
260 ## $a Boston, $b Printed by Rogers and Fowle for Edwards, $c 1744.
300 ## $a 192 p. $c 15 cm.
510 4# $a Evans $u $c 5375

The 510 $u contains the Permalink identifier for the record describing Charles Evans’s American bibliography.

2. Identifier for the description of the resource described in the cited bibliography:

       100 1# $a Adams, John, $d  1662-1720.
245 13 $a An essay concerning self-murther. $b Wherein is endeavour'd to prove, that it is unlawful according to natural principles. With some considerations upon what is pretended from the said principles, by the author of a treatise, intituled, Biathanatos, and others. $c By J. Adams, rector of St. Alban Woodstreet, and chaplain in ordinary to His Majesty. 260 ## $a London : $b printed for Tho. Bennet, at the Half-Moon, in St. Paul's Church-Yard, $c 1700.
300 ## $a [16], 320 p. ; $c 8°.
510 4# $a ESTC, $c R22152 $u X74MUUK734V-01737?func=full-set- set&set_number=144645&set_entry=000001&format=999

The 510 $u contains a persistent URL to the record for Adams’s Essay in the English Short-Title Catalogue at the British Library.

3. Identifier for the description of the resource described in the cited bibliography:

  100 0# $a Abraham a Sancta  Clara, $d 1644-1709.     
  245 10 $a Judas der  Ertz-Schelm, für ehrliche Leuth, oder, 
         Eigentlicher Entwurff, vnd  Lebens-Beschreibung dess 
         Iscariotischen Bösswicht : $b worinnen  vnderschiedliche 
         Discurs, sittliche Lehrs-Puncten, Gedicht, vnd Geschicht, 
         auch  sehr reicher Vorrath Biblischer Concepten : wleche nit 
         ellein einem Prediger  auff der Cantzel sehf dienlich 
         fallen, der jetzigen verkehrten, bethörrten,  versehrten 
         Welt die Warheit vnder die Nasen zu reiben : sondern es kan 
         sich  auch dessen ein Privat- vnd einsamber Leser zur 
         erspriesslicher  Zeitvertreibung, vnd gewünschten Seelen-
         Hayl gebrauchen. $n Der dritte Theil /  $c zusammen getragen 
         durch Pr. Abraham à S. Clara, Augustiner Baarfüsser,  
         Käyserlichen Prediger, vnd der Zeit durch Teutschland 
         Provincialem, &c.      
  260 ## $a Saltzburg : $b In  Verlegung Melchior Haan, einer 
         Löblichen Landschafft, vnd Staat-Buchdruckern  vnd Handlern,
         $c Anno MDCLXXXXII [1692[      
  300 ## $a [24], 556, [16] p.  : $b ill. ; $c 21 cm (4to)   
  510 4# $a VD 17 $c  12:196157F $u

The 510 $u contains a persistent URL to the record for Abrahams’s Judas der Ertz-Schelm in the Verzeichnis der im deutschen Sprachraum erschienenen Drucke des 17. Jahrhunderts (VD 17) database.

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