What is an ISSN-L?

The linking ISSN or ISSN-L enables collocation or linking among different media versions of a continuing resource.

ISSN-L is defined in the new ISO Standard on ISSN.

ISSN-L is an ISSN designated by the ISSN Network to group the different media versions of a continuing resource.

Only one ISSN-L will be designated regardless of how many different medium versions of a continuing resource exist. A continuing resource will be associated with only one ISSN-L.

The ISSN-L is intended to be eye-readable as well as machine-readable.

Examples:

Continuing resource in only one medium form:
ISSN-L 1748-7188 
            Online resource: Algorithms for molecular biology = ISSN 1748-7188

Continuing resources in two medium forms:
ISSN-L 0264-2875 
            Printed version: Dance research = ISSN 0264-2875 
            Online version: Dance research (Online) = ISSN 1750-0095

Continuing resources in three medium forms:
ISSN-L 1188-1534 
            Printed version: Plant varieties journal (Ottawa) = ISSN 1188-1534 
            Online version: Plant varieties journal (Ottawa. Online) = ISSN 1911-1479 
            CD-ROM version: Plant varieties journal (Ottawa. CD-ROM) = ISSN 1911-1460

The serials community, i.e., those involved in the production, distribution, management of, and access to serial resources have expressed the strong desire that the ISSN system meets two different needs:

• The need for the ISSN to identify the various medium versions of a continuing resource, for product management purposes. To meet this need, separate ISSN are assigned to the various medium versions of a resource.

• The need for a collocating, or grouping mechanism that would bring together various medium versions, and thus facilitate content management. The linking ISSN (ISSN-L) has been defined to meet this currently unmet need.

Among other improvements, the Linking ISSN facilitates search, retrieval and delivery across all media versions for services like Open URL, library catalogues, search engines, or knowledge bases. It fosters interoperability by specifying the use of ISSN and ISSN-L with other identification and linking systems such as DOI, Open URL, URN and EAN bar codes.

The designated ISSN-L is available in several different ways:

• via a table which lists the ISSN-L and the corresponding ISSN numbers. This table is available free of charge on the ISSN International Centre web site;

• via the ISSN Register: each metadata record in the ISSN Register includes the medium-specific ISSN assigned to the resource described in the record, and the designated linking ISSN, as separate data elements;

• via ISSN International and National Centres, which communicate to publishers the ISSN-L designated for newly assigned ISSN;

• via the resources themselves, provided that publishers print or display this information according to the recommendations of the standard.

ISSN-L is a separate, specific data element, and is identified in MARC formats by a specific subfield in the tag already used to record the ISSN.

In MARC 21, ISSN-L is included in the subfield “l” of the field 022 (ISSN)

Examples:

Continuing resource in two medium forms
Printed version: 022  $a0264-2875 $l0264-2875
Online version: 022  $a1750-0095 $l0264-2875

In UNIMARC, ISSN-L is included in the subfield “f” of the field 011 (ISSN)

Examples:

Continuing resource in two medium forms
Printed version: 011  $a0264-2875 $f0264-2875
Online version: 011  $a1750-0095 $f0264-2875 

 
Yes, in order for the ISSN-L to work effectively, publishers need to clearly indicate when they are using an ISSN-L as opposed to an ISSN.

The ISO standard recommendations for printing and displaying ISSN-L are as follows: “the linking ISSN shall be clearly distinguished as such by use of the label ISSN-L. In such cases, the label ISSN-L shall be written in uppercase and a space shall precede the 8 digits of the linking ISSN. Example : ISSN-L 0251-1479”.

A new ISSN-L is designated when the titles of all medium versions undergo a major change at the same time. In these cases, a new ISSN is assigned to each version in a specific medium and a new ISSN-L is designated.

Examples:

Printed version:
Acta Physiologica Scandinavica (Print)= ISSN 0001-6772 and ISSN-L 0001-6672

Online version:
Acta Physiologica Scandinavica (Online)= ISSN 1365-201X and ISSN-L 0001-6672
?

Title changes on all medium versions:

?  
Printed version:
Acta Physiologica (Print) = ISSN 1748-1708 and ISSN-L 1748-1708

Online version:
Acta Physiologica (Online) = ISSN 1748-1716 and ISSN-L 1748-1708

ISSN numbers are heavily used in the resolution mechanisms for citation linking in scientific and technical articles, as implemented in the Open URL scheme.

The ISSN-L further enhances this process by allowing for both more precise requests from citations (query strings) and better hit rates at the end of the resolution process.

Query strings generated from citations have the possibility, according to the context, to encode both the ISSN (pointing for example specifically to the electronic resource itself) and the ISSN-L (pointing to the all the different media versions of the publications).

At the other end of the linking chain, the knowledge bases which are key components of Open URL resolution servers have the possibility to associate any ISSN received in a query string to its ISSN-L counterpart and thus to all the linked ISSN identifying the different available media versions.

This should lead to more consistent results, even if different ISSNs are used at both ends of the resolution chain (for instance a “print” ISSN at the citation level and an “electronic” ISSN in the list of serials available through the library).