| Value | Description | Notes | Issue number | Modified in Issue |
|---|---|---|---|---|
| 01 | Proprietary | For example, a publisher’s internal digital asset ID. Note that <IDTypeName> is required with proprietary identifiers | 53 | |
| 09 | ISCC | International Standard Content Code, a ‘similarity hash’ derived algorithmically from the resource content itself (see https://iscc.codes). <IDValue> is the 55-character case-sensitive string (including three hyphens) forming the ISCC of the resource file | 53 |