Aadhaar authentication for GST registration applies to specified persons, with alternate identification allowed where Aadhaar is unavailable. Authentication of possession of Aadhaar number is required, for GST registration purposes, for the authorised signatory of all types, managing and authorised partners of a partnership firm, and the Karta of a Hindu undivided family. Where Aadhaar number has not been assigned, alternate and viable means of identification must be offered in the manner specified in the rules.