Not only is the C4 ID universally unique, it is also universally consistent. This means that given identical files in two different organizations, both organizations would independently agree on the C4 ID, without the need for a central registry or any other shared information. This allows organizations to communicate with others about assets consistently and unambiguously, while managing assets internally in any way they choose.
This can be done without prior agreement or communication of any kind. This ‘agreement without communication’ is an essential feature of C4 IDs and a key differentiator between it and other identification systems.
See the full story here: http://www.etcentric.org/etc-publishes-white-paper-on-c4-cloud-production-framework/