Advance ruling determinations clarify GST treatment for supplies proposed or undertaken by an applicant under the Act. Advance rulings are decisions issued by the Authority or the Appellate Authority on matters specified in the advance ruling provisions concerning supplies of goods or services undertaken or proposed by an applicant. The Authority for Advance Ruling and the Appellate Authority are the statutory bodies to issue such decisions. 'Applicant' includes any person registered or seeking registration under the Act, and 'application' denotes the request submitted to the Authority under the relevant statutory provision.