dc:identifier in wild ePubs
by Liza Daly
Here’s some trivia about the use of the required dc:identifier metadata element in ePubs that have been uploaded to Bookworm to date.
| dc:identifier type | Percentage of total |
|---|---|
| None | 0.5% |
| UUID | 81% |
| ISBN | 2.3% |
| URL | 1% |
| Unknown format | 15.2% |
Although the ePub specification does not describe a particular identifier format, it is strongly recommended that ePub creators use one of ISBN, UUID or URL.
Note: only UUIDs and ISBNs that begin with urn:uuid or urn:isbn are counted here. Assigning either number without the prefix results in them being filed as “unknown.”