The Library of Congress >> Especially for Librarians and Archivists >> Standards

MARC Standards

HOME >> MARC Development >> Discussion Paper List


DATE: May 27, 2016

NAME: Using a Classification Record Control Number as a Link in the MARC 21 Bibliographic Format

SOURCE: German National Library

SUMMARY: This paper explores the options of linking from a MARC Bibliographic record to a MARC Classification record by using the record control number of the MARC Classification record as an identifier.

KEYWORDS: Subfield $0 (BD); Authority record control number or standard number (BD); Classification record control number (BD)

RELATED: 2016-DP19

05/27/16 – Made available to the MARC community for discussion.

06/26/16 – Results of MARC Advisory Committee discussion: There was a general preference for option 1, the expansion of subfield $0 (Authority record control number or standard number) to encompass classification record control numbers rather than defining a new subfield $1 to record this information. If there were any fields besides 084 (Other Classification Number) in which it would be desirable to define subfield $0 for classification record control numbers (as listed in the paper), then details should be provided to the German National Library. In addition $0 should be defined in fields of the MARC Authority Format which carry classification information. The paper will return as a proposal which will consider whether both the Authority and Bibliographic formats should be addressed.

Discussion Paper No. 2016-DP28: Using a Classification Record Control Number as a Link in the Bibliographic Format


Libraries from the Southwestern Regional Library Network of Germany (BSZ/SWB) have started to create classification records for the "urger Verbundklassifikation", a classification system widely spread over German library systems (

The creation and usage of classification records provide a similar level of control and flexibility as the creation and usage of authority records: In the classification record the information about a single entity is given, by textual notes, by codes and by relationships (e.g. hierarchical, chronological) to other entities inside of the classification file, all based on the systematic approach that the classification system takes. A link to this classification record from a field of the bibliographic record then can provide "classification control" (similar to "authority control"), using the record control number of the classification record as a way to identify the entity described in the classification record.

In our specific case, to control a field 084 (Other Classification Number) the intention is to have the classification number in $a (Classification number) and the value "rvk" in $2 (Number source), and in addition to provide a link to the classification record, using the record control number of the classification record.

Other classification fields of the MARC Bibliographic format may be enriched accordingly, among them:

050 - Library of Congress Call Number (R)
052 - Geographic Classification (R)
055 - Classification Numbers Assigned in Canada (R)
060 - National Library of Medicine Call Number (R)
070 - National Agricultural Library Call Number (R)
080 - Universal Decimal Classification Number (R)
082 - Dewey Decimal Classification Number (R)
083 - Additional Dewey Decimal Classification Number (R)
085 - Synthesized Classification Number Components (R)
086 - Government Document Classification Number (R)


Field 084 is currently defined in the Bibliographic format as follows:

084 - Other Classification Number (R)

First Indicator: # - Undefined

Second Indicator: # - Undefined

Subfield Codes

$a - Classification number (R)
$b - Item number (NR)
$q - Assigning agency (NR)
$2 - Number source (NR)
$6 - Linkage (NR)
$8 - Field link and sequence number (R)

Field Definition and Scope
Classification number from a scheme not covered by one of the other number fields. The field should not be used for classification numbers assigned from a source for which a subfield $2 source of number code would not be assigned.

The MARC code list used for $2 is the list of "Classification Scheme Source Codes", online at

On the list, there is an entry "rvk" for the "urger Verbundklassifikation (RVK)", pointing to the RVK web page at

Defining one additional subfield for a link to a classification record by using its record control number seems to be a way of solving the issue.

2.1. OPTION 1

Exploring this path, a good candidate may be the subfield $0, which in Appendix A: Control Subfields of the Bibliographic Format is defined as follows:

$0 - Authority record control number or standard number
Subfield $0 contains the system control number of the related authority record, or a standard identifier such as an International Standard Name Identifier (ISNI). The control number or identifier is preceded by the appropriate MARC Organization code (for a related authority record) or the Standard Identifier source code (for a standard identifier scheme), enclosed in parentheses. See MARC Code List for Organizations for a listing of organization codes and Standard Identifier Source Codes for code systems for standard identifiers. Subfield $0 is repeatable for different control numbers or identifiers.

NOTE: Subfield $0 is sometimes referred to in the field descriptions as Authority record control number.

100 1#$aBach, Johann Sebastian.$4aut$0(DE-101c)310008891

100 1#$aTrollope, Anthony,$d1815-1882.$0(isni)0000000121358464

Subfield $0 would have to be broadened in scope, to accommodate Classification record control numbers, in addition to Authority record control numbers and standard numbers.

So option 1 suggests:

- Broadening the scope of subfield $0 from "Authority record control number or standard number" to "Authority or Classification record control number or standard number". A shorter name should be discussed;

- Defining subfield $0 as a repeatable subfield in field 084 of the Bibliographic format.

2.2. OPTION 2

Instead of re-using subfield $0, a new subfield may be defined. The only remaining numerical subfield code is "$1". The structure of $1 may be defined similar to the structure of $0.

So option 2 suggests:

- Defining subfield $1 as "Classification record control number".
It might instantly be taken into account that not only a record control number (e.g. field 001) of the target classification record can be used, but also other numbers, as standard numbers and identifiers, including a URI. It should be noted here that field 024 (Other identifier) is not yet defined in the MARC Classification format. Following this would result in naming $1 as "Classification record control number or standard number";

- Defining subfield $1 as a repeatable subfield in field 084 of the Bibliographic format.


3.1. According to option 1, with subfield $0:

084 ## $aPS 4080$0(DE-576)201436450$2rvk
084 ## $aPS 4100$0(DE-576)201239000$2rvk
084 ## $aST 601$0(DE-576)20114283X$2rvk
084 ## $aZN 6040$0(DE-576)200877518$2rvk

3.2. According to option 2, with subfield $1:

084 ## $aPS 4080$1(DE-576)201436450$2rvk
084 ## $aPS 4100$1(DE-576)201239000$2rvk
084 ## $aST 601$1(DE-576)20114283X$2rvk
084 ## $aZN 6040$1(DE-576)200877518$2rvk


"DE-576" is the ISIL = MARC Organization Code for the Southwestern Regional Library Network (see entry at

The classification RVK itself has an ISIL = MARC Organization Code "DE-625" on its own (see entry at


The record control numbers in the MARC records have the potential to support the transformation of data into BIBFRAME.


5.1. Is the need of controlling a classification field by using an identifier from a classification record a clearly given one?

5.2. Would the definition of subfield $0 (Authority record control number or standard number) in field 084 be a feasible way (option 1)?

5.3. Should subfield $0 (Authority record control number or standard number) generally be re-defined to cover an "Authority or classification record control number or standard number"?

5.4. Or should a new numeric control subfield "$1" be defined to accommodate a "Classification record control number" (Option 2)?

5.5. Are there any potential problems that should be taken into account?

HOME >> MARC Development >> Discussion Paper List

The Library of Congress >> Especially for Librarians and Archivists >> Standards
( 07/12/2019 )
Legal | External Link Disclaimer Contact Us