Any choice in the assignment of a prefix for DOIs?

I understand that DOIs are supposed to be opaque identifiers, and that DOI prefixes are 10. followed by a registrant code of 4+ digits (apparently with with possible subdivisions that I’m not interested in). Beyond these requirements, is there any choice of the registrant code (prefix) that is described in the DOI documents? Who selects the registrant code?

Hi, and thanks for your question.

No, the DOI prefixes aren’t chosen. They’re assigned arbitrarily when an organization completes the application process to join Crossref as a member.