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 you 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.
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 instance above, the publisher has put 15, which is the ONIX code for 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. (See Appendix A for this list.)|
|<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.|
|<b244>||<IDValue>||This is where you put the actual ID; your ISBN, ISTC, or proprietary code. The length of this field and validation will depend on your code for your WorkIDType. If it’s an ISBN-13, you need all 13 numbers. If it’s a proprietary code, the length is as long as you need it.|
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 Code List 16, Work identifier type code
ONIX Code Lists Issue 11, March 2010
List 16: Work identifier type code
|02||ISBN-10||10-character ISBN of manifestation of work, when this is the only identifier available|
|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|