Non-repudiation is the assurance that someone cannot deny something. Digital IDs and SSL certificates provide non-repudiation because they guarantee the authenticity of a document or message. As a result, the sending parties cannot deny that they sent it (they cannot repudiate it).
The Data Universal Numbering System (DUNS) number is a unique nine-digit identification number created and provided by Dun & Bradstreet (D&B). The DUNS number is specific for each location of an entity such as HQ, divisions and branches.