| 01 | Unknown | | 0 | |
| 02 | Anonymous | Note that Anonymous can be interpreted as singular or plural. A real name can be provided using <AlternativeName> where it is generally known | 0 | 49 |
| 03 | et al | And others. Use when some but not all contributors are listed | 0 | |
| 04 | Various | When there are multiple contributors, and none are listed individually. Use for example when the product is a pack of books by different authors | 1 | 49 |
| 05 | Synthesised voice – male | Use with Contributor role code E07 ‘read by’, eg for audio books with digital narration | 8 | 49 |
| 06 | Synthesised voice – female | Use with Contributor role code E07 ‘read by’, eg for audio books with digital narration | 8 | 49 |
| 07 | Synthesised voice – unspecified | Use with Contributor role code E07 ‘read by’, eg for audio books with digital narration | 8 | 49 |
| 08 | Synthesised voice – based on real voice actor | Use with Contributor role code E07 ‘read by’, eg for audio books with digital narration, and provide name of voice actor in <AlternativeName>. Only for use in ONIX 3.0 or later | 49 | |
| 09 | AI (Artificial intelligence) | Use when the creator (of text, of images etc) is a generative AI model or technique. Note, can also be combined with the role ‘assisted by’. Only for use in ONIX 3.0 or later | 62 | |