What is a Work Identifier?

The <workidentifier> in your ONIX is the element that links together all the different assets associated with a single title. The identifier for a title can be any unique code you like, from a proprietary identifier that you use in-house, to a print ISBN, to an International Standard Text Code (or ISTC – a code that identifies a work, and not just a single book).

If you are using a digital asset management system, like CoreSource, all assets associated with a single title (including EPUB files, cover images, InDesign files, POD and PDF) will be linked together by the work identifier element.

Consistency is key

The most important thing to remember about the work identifier is that it must remain consistent across your records for a title. If you are publishing The Big Book of Data Success, and are using the print ISBN as the work identifier to mark the record for your print book, but have an ISTC for your EPUB record and PDF, your digital files will be treated as a separate title from your print book, and your assets will be impossible to group.

The work identifier comes after the <title> grouping in your ONIX.

Show me the ONIX


The above group is the minimum necessary for a proper work identifier. Below, we’ve added an optional tag to describe the identifier a little more in-depth.

<b233>Hardcover ISBN</b233>

Break it down

Let’s have a look at that line by line. We’ll look at both the short tag and reference tags

Short Tag Reference Tag
<workidentifier> <WorkIdentifier> These tags mark the beginning and end of the ONIX group.
<b201> <WorkIDType> This identifies what type of identifier you are using as your work identifier. In our example above, the publisher has entered 15, which according to ONIX code list 16, is the indicates that the work identifier is an ISBN-13. If you wanted to put in a proprietary number, you would replace the 15 with 01, signifying that the ID you are using is original to your company.
<b233> <IDTypeName> A free-text field where you can put a short description of the identifier. It is recommended that you have no more than 50 characters here.

If you take one thing away, it should be this:

It bears repeating: the most important part of using a work identifier is to be consistent. If you have separate identifiers for different formats of the same title, you could easily lose track of those assets. If you treat your work identifier right, your work identifier will return the favour.

Appendix A: ONIX Work Identifier Type Codes

ONIX Code Lists Issue 29, April 2015
List 16: Work identifier type code

Value Description Notes
01 Proprietary
02 ISBN-10 10-character ISBN of manifestation of work, when this is the only identifier available – now DEPRECATED in ONIX for Books, except where providing historical information for compatibility with legacy systems.
06 DOI Digital Object Identifier (variable length and character set)
11 ISTC International Standard Text Code (16 characters: numerals and letters A-F, unhyphenated)
15 ISBN-13 13-character ISBN of manifestation of work, when this is the only identifier available
18 ISRC International Standard Recording Code


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