Which metadata field in the DataCite schema captures the grant ID information?

The “awardURI” field in the DataCite metadata schema is the appropriate place to include a URI for a grant. This is also the correct place to enter a DOI for grants registered with the Crossref Grant ID Service.

Example:

<awardNumber awardURI="http://cordis.europa.eu/project/rcn/100603_en.html”>284382

The URI and award number don’t need to match, in the above example the URI (not a DOI in this case) doesn't contain any part of the actual award number, but if you follow the link, you'll see that the "grant agreement ID" assigned by the EU is the “awardNumber” listed in the metadata.

More information:

DataCite metadata schema