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DATE: May 27, 2021

NAME: Recording Cluster ISSNs in the MARC 21 Bibliographic, Authority, and Holdings Formats

SOURCE: ISSN Review Group

SUMMARY: This paper discusses the need for a new field, field 023, to record Cluster ISSNs in MARC 21 records. The Cluster ISSN is a new concept defined in ISO 3297:2020. Cluster ISSNs are identifiers intended to provide a mechanism to group various categories of related continuing resources. The ISSN-L is the first example of a Cluster ISSN and is currently recorded in 022 $l.  During the January 2021 MAC meeting, URI subfields $0 and $1 were approved for field 022. Anticipation of future Cluster ISSNs with their associated URIs necessitates a new repeatable field to provide a separate field for each Cluster ISSN and its associated URIs.

KEYWORDS: Field 023 (AD, BD, HD); Field 022 (AD, BD, HD); International Standard Serial Number (AD, BD, HD); Cluster ISSN (AD, BD, HD); ISSN (AD, BD, HD); Linking ISSN (AD, BD, HD); ISSN-L (AD, BD, HD)

RELATED: 2007-DP032007-05; 2020-DP11; 2021-04

05/27/21 – Made available to the MARC community for discussion.

06/28/21 – Results of MARC Advisory Committee discussion: There was support for a new field for Cluster ISSNs but a clearer definition of the Cluster ISSN concept was requested as well as use cases illustrating the needs that Cluster ISSNs would meet. There was some concern about the effect on consortia of deprecating 022 $l and $m but the apparent absence of problems with the previous move of ISSN data from the Leader to 022 $2 was cited. When introducing the paper, a new plan to develop a controlled vocabulary of Cluster types and associated URIs maintained by the ISSN International Centre instead of using indicator values was presented. Some felt use of URIs for both the Cluster identifier and Cluster type might be confusing but $4 was suggested as being used in comparable situations. The paper will likely return as a proposal.

Discussion Paper No. 2021-DP07: Recording Cluster ISSNs


The most recent revision of the International Standard, ISO 3297, Information and documentation - International Standard Serial Number (ISSN), was published in October 2020 following its adoption as the sixth edition of the ISO ISSN Standard by the ISO Member Bodies. One outcome of this revision was the concept of Cluster ISSN, which expanded the grouping of ISSNs exemplified by the Linking ISSN (ISSN-L) to provide for the identification of additional specific groups of ISSN, such as those related by former and later relationships (sometimes referred to as "family ISSN") or language or geographic editions.


The need for ISSN-L, the first Cluster ISSN, was based on one of two needs identified by members of the serials community (those involved in the production, distribution, management of, and access to serial resources) during the revision of the ISSN standard that resulted in ISO 3297: 2007. The first need was to identify each specific medium version of a continuing resource by assigning an ISSN and creating a record for each. The second need was for a grouping mechanism to bring together the various medium versions of a serial to facilitate content management and resolution services which led to the definition of the ISSN-L. The 2020 revision of the ISSN standard recognizes that there are other potential groups of continuing resources that are relevant to the community, such as geographic editions, language editions, and a group that includes all earlier and later titles. Provision for additional Cluster ISSNs was therefore included in the revised ISO standard.

A mechanism for grouping earlier and later titles of a serial has been of particular interest to the library community but also of interest to the indexing and publishing communities. Such a mechanism can help alleviate searching problems caused by new ISSNs assigned as a result of major title changes. Conference publications are notorious for changes in both the conference title and the proceedings title, with the result that what users conceptualize as one conference might be represented by four or five different ISSNs and bibliographic records over its lifetime. A Cluster ISSN sometimes called a "family ISSN" could be implemented to retrieve or identify the entire title history.

2.1. New Field Needed

The new ISO ISSN standard stipulates that the Cluster ISSN is a new and separate data element, distinct from the medium-specific ISSN. Thus, a Cluster ISSN has its own URI in the ISSN Portal whose syntax is defined by the ISO standard. Additionally, discussions during the consideration of 2020-DP11 and Proposal 2021-04 to add URI subfields to field 022 brought forward the need to distinguish URIs for the Linking ISSN from the URIs for the ISSN in 022 $a. Defining a new repeatable field for Cluster ISSNs, field 023, will provide both a separate field for each Cluster ISSN as well as allow URIs to be correctly associated with each Cluster ISSN.

The proposed 023 field is defined as repeatable so that each specific Cluster ISSN can have its own field where any URI is associated only with that Cluster ISSN. Indicator values will be defined to denote specific types of Cluster ISSN. At present the ISSN-L is the only Cluster ISSN.

2.2. Change in Field 022

Currently, field 022 (the ISSN field) contains indicators usually only provided by ISSN assigning agencies to denote whether a publication is of international or local interest. It contains the following subfields:  $a (ISSN); $y (Incorrect ISSN); $z (Canceled ISSN); $l (ISSN-L), for linking ISSN; $m (Canceled ISSN-L); and $2 (Source), for ISSN center code. If a new field is defined for Cluster ISSNs, it will be necessary to make $l (ISSN-L) and $m (Canceled ISSN-L) obsolete in field 022. Making these subfields obsolete for field 022 will clarify that any URIs in field 022 pertain to the ISSN in $a since any remaining ISSNs will be in $y or $z which are designated for incorrect or canceled ISSNs respectively and thus should not be associated in field 022 with URIs.

The ISSN International Centre (ISSN IC) is prepared to move all data in 022 $l and 022 $m in the ISSN Register to field 023. A new cataloging and data management system for the ISSN IC, ISSN Plus, will facilitate this move. The ISSN International Centre will continue making available tables that link Cluster ISSNs with ISSNs, now exemplified by the ISSN-L correspondence tables.


3.1. Definition of Field 023

The proposed new field, 023, is for a repeatable field intended to contain Cluster ISSNs whether currently defined, i.e., ISSN-L, or to be defined in future such as a possible ISSN-F or "family ISSN" according to the provisions of ISO 3297:2020.  The field adopts some of the structure of field 022, the ISSN field, by including specific subfields for incorrect and canceled Cluster ISSNs, $0 and $1 for corresponding URIs, and $2 for the responsible ISSN center.

In the MARC 21 Bibliographic, Authority, and Holdings Formats, define field 023 as follows:

023 – Cluster ISSN (R)

First Indicator: Type of Cluster ISSN
Cluster ISSNs are a mechanism defined in ISO 3297:2020 to provide for the identification of specific groups of ISSN, such as the various medium editions of a continuing resource or serials related by former and later relationships. (sometimes referred to as “Family ISSN”) or language or geographic editions.

0 - ISSN-L 
Links together the various media versions of a continuing resource. ISSN-L may be generated for display.

1-8 available for future Cluster ISSN types

Second Indicator: Undefined

Subfield Codes

$a - Cluster ISSN
Valid Cluster ISSN for the continuing resource identified in field 022 $a. Cluster ISSNs group together resources with specific relationships to each other such as medium versions (ISSN-L), and future clusters such as earlier and later titles (yet to be defined). The appropriate prefix for the ISSN type denoted by the first indicator value may be generated for display, e.g., for value 0: ISSN-L.

$y – Incorrect Cluster ISSN
Cluster ISSN that has been incorrectly associated with the continuing resource or incorrectly formatted on the resource. Each incorrect Cluster ISSN is contained in a separate $y.
E.g., ISSN-L (incorrect) may be generated for display.

$z - Canceled Cluster ISSN
Cluster ISSN that has been associated with the resource but subsequently canceled, often because a duplicate Cluster ISSN was assigned. Each canceled Cluster ISSN is contained in a separate $z. 
E.g.,  ISSN-L (canceled) may be generated for display.

$0 – Authority record control number or standard identifier
A URI for the Cluster ISSN in subfield $a
See description of this subfield in Appendix A: Control Subfields.

$1 - Real World Object URI
See description of this subfield in Appendix A: Control Subfields.

$2 - Source
ISSN Center responsible for assigning and maintaining ISSNs, Cluster ISSNs, and related data. Code from ISSN National Centres code list online at:, National Centres.

$6 - Linkage

$8 - Field link and sequence number

3.2. Make Subfields $l and $m Obsolete in Field 022

In Field 022 (International Serial Number) of the MARC 21 Bibliographic, Authority, and Holdings Format, make the following subfields obsolete:

$ l - ISSN-L (R)
$m - Canceled ISSN-L (R)


Note: The examples include hypothetical situations to illustrate usage. Examples that show $0 and $1 are presented from the perspective of the ISSN International Centre since the PCC and others in the community have not fully resolved questions about the content of these subfields.

Example 1: Linking ISSN

022 0 # $a 1476-4687 $2 2 $0
023 0 # $a 0028-0836 $2 2 $0
222 # # $a Nature $b (Basingstoke. Online)
245 1 # $a Nature.

Example 2: Linking ISSN with incorrect ISSN-L

022 0 # $a 0151-4105 $2 7 $0 $1
023 0 # $a 0151-4105 $2 7 $y 0048-7996 $1
222 # # $a Revue d'histoire des sciences
245 1 # $a Revue d'histoire des sciences.

Example 3: Linking ISSN with canceled ISSN-L

022 0 # $a 1043-0253 $2 1 $z 0147-8745 $0
023 0 # $a 1043-0253 $2 1 $z 0147-8745 $0
222 # 0 $a Fodor's USA
245 1 0 $a Fodor's USA.

Example 4: Future Family ISSN

022 0 # $а 1063-3928 $2 1 $0
023 0 # $а 1063-3928 $2 1 $0  
023 1 # $a 9999-9999 $2 1  $0  
222 0 # $a Conference record of the IEEE Particle Accelerator Conference
245 0 0 $a Conference record of the IEEE Particle Accelerator Conference
780 0 0 $t Proceedings of the IEEE Particle Accelerator Conference $x 1063-3936
785 0 0 $t Proceedings of the Particle Accelerator Conference $x 1529-7969


Currently, BIBFRAME has a specific element at the Work level for "ISSN-L." It is a repeatable element that may be possible to change to a "Cluster ISSN." The element could include a provision to indicate specific types of Cluster ISSNs, such as ISSN-L and ISSN-F.


6.1. Is a new field for Cluster ISSNs needed?

6.2. What problems might the addition of the new field cause?

6.3. What problems might be caused for those organizations that use Linking ISSN data by the change from locating ISSN-L data in field 022 to locating ISSN-L data in field 023?

6.4. What problems might be caused if 023 is implemented by some organizations and not others?

6.5. Is there any potential for confusion in using $y and $z for incorrect and canceled Cluster ISSNs in order to align with the subfields for incorrect and canceled ISSNs in field 022?

6.6. Are there any additional issues or possible consequences of the suggested changes that have been overlooked?

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