| Value | Description | Notes |
|---|---|---|
| 01 | Proprietary | |
| 02 | ISBN-10 | 10-character ISBN of manifestation of work, when this is the only work identifier available – now DEPRECATED in ONIX for Books, except where providing historical information for compatibility with legacy systems. It should only be used in relation to products published before 2007 – when ISBN-13 superseded it – and should never be used as the ONLY identifier (it should always be accompanied by the correct GTIN-13 / ISBN-13 of the manifestation of the work) |
| 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 work identifier available |
| 18 | ISRC | International Standard Recording Code |