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4.4. Identifiers assigned by the Publications Office

Since 2001 the Publications Office has acted as the official agency assigning the following identifiers to publications issued by European Union institutions, bodies and organisations: international standard book number (ISBN); international standard serial number (ISSN) for serial publications and other continuing resources; and digital object identifier (DOI). These international identifiers are used to classify publications all over the world in an unequivocal and exclusive way. An internal identifier (catalogue number) is also assigned for every product (book, leaflet, poster, etc.) in any format (paper, electronic, CD/DVD, etc.).

In order for an identifier to be assigned to a work, the originating services must provide the Publications Office with two physical copies of the work, in addition to sending the electronic version (PDF).

The Publications Office automatically assigns an identifier whenever it receives a publication request.

4.4.1. International standard book number (ISBN)

Any monographic publication (see Section 4.3.1) is assigned an international standard book number (ISBN) by the Publications Office.

The assignment of an ISBN has no legal meaning or value with regard to the copyright of the work concerned or its content.

An ISBN cannot be modified, replaced or reused once it has been assigned to a product.

A separate ISBN is required for:

In the case of multiple volumes, an ISBN is assigned to each volume and a collective ISBN is assigned to the set of volumes. The collective ISBN and the ISBN of the respective volumes must be printed on the reverse of the title page of each volume.

Where a publication is published jointly or as a co-edition by two or more publishers, each publisher may assign its own ISBN and display it on the copyright page. However, only one ISBN in barcode form must appear on the back cover or dust jacket of a publication.

An ISBN must also be assigned to loose-leaf publications with a predetermined publication end date (i.e. which are not intended to be published indefinitely). On the other hand, continually updated loose-leaf publications (integrated resources) or updated individual parts must not be assigned an ISBN.

ISBN location and display

The ISBN, which must always appear on the product itself, has since 1 January 2007 comprised 13 digits organised into five groups, preceded by the prefix ISBN followed by a space:

ISBN 978-92-79-00077-5

Printed publications

For printed publications, the ISBN must be printed together with all other identifiers on the reverse of the title page (see example in Section 5.3.1). If that is not possible, it must appear at the bottom of the title page or be included with the copyright notice.

It must also appear on the lower portion of the back cover (and the lower portion of the dust jacket) (see example in Section 5.1.1).

Electronic publications or other types of non-printed products

For online publications, the ISBN must be included on the title screen or its equivalent, and/or on the screen displaying the copyright notice.

For any other product (CD-ROM, DVD, etc.), the ISBN must appear on a label permanently affixed to the product or, if that is not possible, on the lower portion of all the product’s permanent packaging (box, sleeve, holder, etc.).

The ISBN must also be included in all metadata contained within the publication or product.

In the case of a publication in different formats, only one ISBN is required if they are packaged together; if they are distributed separately, each version must be assigned an ISBN. Furthermore, all ISBNs must be listed together in each version, with a brief indication of the format, as in the following example:

Print PDF EPUB HTML

ISBN 978-951-45-9693-3 ISBN 978-951-45-9694-0 ISBN 978-951-45-9695-7 ISBN 978-951-45-9696-4

The ISBN must also be indicated on any material accompanying the publication.

4.4.2. International standard serial number (ISSN)

Continuing resources (serial publications and ongoing integrating resources – see Section 4.3.2) must be identified by an international standard serial number (ISSN), which is assigned by the Publications Office.

The allocation of an ISSN has no legal meaning or value with regard to the copyright of the work concerned or its content.

An ISSN is assigned exclusively for:

In the case of multiple volumes, an ISSN is assigned to the key title, regardless of the number of volumes it comprises. An ISSN can also be assigned to a collection of monographs as such, with an ISBN being assigned to each volume in the collection.

The ISSN is permanently associated with a ‘key title’, created by the ISSN network at the time the resource is registered. The key title is unique to each specific continuing resource.

A new ISSN (and a new key title) must be assigned to a continuing resource if:

Any supplement or sub-series that may accompany a continuing resource must be assigned its own ISSN (and thus a specific key title).

ISSN location and display

An ISSN is composed of two groups of four digits (Arabic numerals) separated by a hyphen and preceded by the letters ISSN followed by a space. The last character (the control character) may be an X:

ISSN 0251-1479

ISSN 1831-855X

The ISSN must be printed clearly on or in the first issue of a serial publication and on or in any subsequent issue, as well as on or in each version of an ongoing integrating resource.

Where an ISSN is accompanied by another identifier, such as an ISBN in the case of a volume in a collection, the two numbers must appear together, each identified by the required prefix (ISBN, ISSN, DOI, etc.).

If a continuing resource has been assigned several ISSNs for different titles (such as the title of a main collection and the titles of its sub-collections), all the ISSNs must be printed on the resource, and be distinguished by the inclusion of (for example) the complete or abridged title in brackets.

In the case of publication in different formats (which are assigned different ISSNs and key titles), the relevant ISSNs may appear on the continuing resources, distinguished as in the following example:

Print HTML

ISSN 1562-6585 ISSN 1063-7710

For printed works, the ISSN must appear on each issue, in the upper right-hand corner of the cover or, if that is not possible, printed clearly and visibly on one of the following (in order of preference): title page, sleeve, data box, back cover, copyright page or masthead area.

For works in electronic format (online works, CD-ROM, etc.), it must be included on the title screen or, if that is not possible, on the main menu, and also, if possible, on any label permanently affixed to the publication. If it is not possible to display the ISSN on the product or its label, it must appear on the container.

For online resources, the ISSN must also appear in the metadata (in the identification field).

Linking ISSN (ISSN-L)

Pursuant to ISO 3297:2017 (ISSN), a linking ISSN (ISSN-L) is assigned to a continuing resource (see Section 4.3.2) to link together the various medium versions of the resource, regardless of the number of versions (each version must itself be assigned a separate ISSN).

The ISSN-L is composed of a sequence of two groups of four digits separated by a hyphen and preceded by the letters ISSN-L followed by a space, as in the following example:

ISSN-L 0251-1479

An ISSN-L must be changed when the titles of all medium versions of a resource undergo a major change at the same time. A new ISSN is then assigned to each separate version and a new ISSN-L to the collection.

4.4.3. Digital object identifier (DOI)

The digital object identifier (DOI) system is used for identifying a product in a digital environment and is designed to ensure the perenniality of hypertext links. It may be applied to:

Each DOI is unique and permanent. A document keeps the same DOI for its entire lifetime and, if ever the document is deleted, the DOI will not be reused.

The DOI number is composed of a prefix and a suffix, separated by a forward slash. It must be in the following format (preceded by the lower-case letters ‘doi’ followed by a colon, with no space):

doi:10.2788/14231

In principle, the location of the DOI follows the same rules as the ISBN or ISSN.

4.4.4. Catalogue number

In addition to the international identifiers, all works created by the Publications Office are assigned an internal identifier, i.e. a catalogue number.

This is an internal Publications Office management tool, used for distribution purposes. It is used to categorise publications in catalogues, among other things. It is also used as an identification key in various IT applications.

The catalogue number is printed on the back cover, in the upper right-hand corner; if that is not possible, it must be clearly visible elsewhere on the work.