Publishers may now include non-Crossref DOIs in Crossref DOI deposits. These DOIs will be deposited as components. This feature allows publishers to deposit journal article or book DOIs and describe their association to content which has been assigned a DOI by another Registration Agency. Including a non-Crossref DOI in a deposit does not affect the registration of the DOI with Handle but the metadata for the DOI is added to the Crossref database. For example, a journal article could define a relationship to a database which has been assigned a DOI via DataCite.
When depositing and registering a component DOI with Crossref, the DOI is enclosed within the <doi_data> element, which also encloses URL(s) within the <resource> and <collection> elements. Non-Crossref DOIs should be included within a <doi> tag, the <doi_data> element is not allowed:
<description>Dataset for parent article</description>
Components are currently how Crossref supports the identification of supplemental material. This feature will be enhanced to reflect terminology and organization defined by the NISO/NFAIS Supplemental Journal Article Materials Project.