Who could prefer an appeal before the Appellate Authority

Following could prefer an appeal before the Appellate Authority:
(a) Any person aggrieved by the order or decision of the adjudicating authority
[FORM GST APL-01Chapter-XIII – Appeals and Revision of the CGST Rules]
(b) Any authorised officer on direction of the Commissioner (this is referred to as application and filed in FORM GST APL-03).

(ICAI FAQ PUBLICATIONS 06-09-2017 APPEALS AND REVISIONS : FAQ NO. 3)