Type of document identifier (for example, a DOI or a publisher’s identifier) named in the @document-id attribute of the <related-object> element to identify a document.
| Value | Meaning |
|---|---|
| The type of document identifier of the related object, for example, a DOI | The type of document identifier named in the @document-id attribute for a (<related-object>) element. This attribute qualifies the @document-id attribute. |