DATE: December 11, 1998

NAME: Defining URL/URN subfields in fields other than field 856 in the MARC Bibliographic/Holdings Formats

SOURCE: Library of Congress; ALCTS Preservation and Reproduction Section, Intellectual Access Committee

SUMMARY: This paper discusses the possibility of defining subfields to record URLs and/or URNs in various fields in the bibliographic format. Some MARC users have requested that a link to a Web resource be provided in fields of the format other than field 856. These include field 037 (Source of Acquisition) for online ordering and field 583 (Action Note) for the location of supplemental information concerning preservation actions.

KEYWORDS: Field 037 (BD); Field 583 (BD/HD); Uniform Resource Locator; Uniform Resource Name; Source of Acquisition (BD); Action Note (BD/HD);

RELATED: DP87 (June 1995); 97-9 (June 1997)


12/11/98 - Forwarded to the MARC Advisory Committee for discussion at the January 1999 MARBI meetings.

1/31/99 - Results of MARC Advisory Committee discussion - There was interest in exploring the definition of URL subfields in other MARC fields in a proposal. Some participants felt that a specific subfield for the URL is preferable to including as text in notes to facilitate updating them later. Fields other than those specifically discussed in the paper might also be considered, e.g. field 545 (Biographical or Historical Data) and field 555 (Cumulative Index/Finding Aids Note). A simple rule is needed so that the user can determine whether to record the URL in field 856 or another appropriate field (e.g., if the URL refers to the title in 245 it is recorded in 856). Guidelines are needed for the further definition of URL subfields in other fields because of the danger of proliferating URLs in a record.

DISCUSSION PAPER NO. 112: Defining URL/URN subfields


Field 856 of the MARC formats includes a subfield $u that contains a Uniform Resource Locator to allow for location and access to electronic documents. In many systems, it allows the system to automatically retrieve and display the resource to which the record is linked via the 856 field, and in Web presentations of MARC records it creates the link. Field 856 has been used to link to an electronic resource that may be related in various ways to the item described in the record. It may link to the resource described in the record (i.e., an electronic resource); it may link to an online version of the resource when the record describes the original; it may link to a subset of the record; or, it may link to a related resource. The link may be only to a subset of the resource described or to the entire resource. In addition, the field may be repeated for other reasons, such as different versions (e.g. jpeg vs. gif), different access methods, or different subsets of the resource.

Discussion Paper No. 87 (Addition of Subfield $l (Uniform Resource Locator) in Linking Entry Fields 76X-78X in the USMARC Bibligraphic Format) was presented at the MARC Advisory Committee meetings in June 1995. The paper suggested that a subfield for a URL be defined in the linking entry fields so that a machine link could be provided to a related electronic resource. This would enable the user to link to the related resource without having to go to the record for that resource itself.

The discussion of this paper revealed concerns about defining a subfield for a URL in the linking entry fields because of 1) the changeable nature of URLs; 2) participants thought it preferable to only include the URL in the record for the resource itself ; and 3) it would encourage people to create links without creating the bibliographic record. The group did not request that the issue come back as a proposal. The issue of the changeability of URLs is relevant in any discussions of defining additional subfields in fields other than 856.

Because of the potential of having several 856 fields in the record for varying purposes, an indicator was defined in the field with Proposal No. 97-01 to indicate the relationship of the data in the field to the resource described in the record. The indicator values distinguish between an 856 that describes the resource itself, an electronic version of the resource described, and a related resource.


2.1 MARC fields that might include a URL/URN

Various users of the format have suggested that URLs be included in other fields where it would be appropriate to have a machine link to an electronic resource. Because a subfield $g was recently defined for a Uniform Resource Name (URN) and the work on standardization of the URN proceeding, any proposal for defining new URL subfields should also include the definition of a MARC element for a URN. This paper uses the term URI to refer to both a URL and URN. A need has been expressed for the definition of a URI subfield in the following fields:

Certainly other fields might be appropriate in which to define a URI, such as field 505 (Formatted Contents Note), 520 (Summary, etc.). However, this paper deals only with those fields for which a specific request has been made.

2.2 Field 037

Field 037 (Source of Acquisition) includes subfields, among others, to include a stock number, the source of that number (which includes an institution and address), and terms of availability (a price). Because of the increased frequency of Web-accessible order information for documents, it is desirable to allow for an electronic address to be recorded in this field. According to the Government Printing Office, some GPO-distributed documents may be only available through a Web site. The URI for an order form could be included in a new subfield to provide a link for ordering (essentially an electronic address comparable to the mail address in 037 subfield $b). The following subfields in field 037 are currently defined:

2.3 Field 583

The ALCTS Preservation and Reproduction Section, Intellectual Access Committee, has requested that subfield $u be defined in field 583 (Action Note) to record the location of external or supplemental information maintained on the Internet or in local automated files. Examples cited are the following:

583 27 $a deacidify $c 19860501 $u
An item that has been deacidified and for which treatment informaton is available through the World Wide Web at the specified URL.

583 27 $a house $c 19841221 $u http://karamelik.eastlib.ufl.edu/cgi-bin/conserve/rara.pl
An item that has been housed and for which housing informaton is available through the World Wide Web at the specified URN.

583 17 $a archive $c 19850603 $u file://i:\repro\storage\storage.dbf
A master negative microfilm that has been archived and for which storage informaton is available in a local file.

The following subfields in field 583 are currently defined:

2.6 Recording URNs

Proposal No. 97-9 (Renaming of Subfield 856$u to Accommodate URNs) was approved in June 1997. Instead of renaming subfield $u as URI to accommodate both URLs and URNs, it defined a different subfield for the URN. Consequently, subfield $g, which had not yet been used, was redefined as URN, to include all kinds of Uniform Resource Names (e.g. DOIs, handles). The subfield has not been used widely yet, but it is likely that in the future URNs will become more prevalent on the Web as persistent names for electronic resources. For consistency with field 856 and to allow for separately identifying URLs and URNs, the addition of new subfields for URLs in other fields should also include new subfields for URNs.

Field 037 has subfield $u available, but subfield $g is defined provisionally as Additional format characteristics. Field 583 has both subfields $g and $u available.


1. Is the argument that URLs are changeable reason not to define them in other fields of the format, given the increasing use of field 856? Does the likely use of URNs in the future make this argument untenable?

2. Since many systems and browsers already recognize a URL even if it is not separately designed as one, is it necessary to provide separate subfields for URIs? Could they just be included in note subfields as necessary?

3. What sort of guidelines will be needed if URIs are allowed in other fields as to when to record the URL/URN in field 856 and when to record in the other field?

4. Will the definition of URIs in these specified fields open up the format for the definition of the same in many different fields? How would this affect the use of the records, given that the URL is changeable? Should they be defined only when an institution submits a specific request?

5. Might commercial publishers want to use a URL subfield in field 037? Are there any problems with commercial use, and should there be any restrictions?

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