Advance Rulings Authority now defined to include bodies constituted or authorised under the Customs Act for advance rulings. The amendment replaces clause (e) of section 23A to define Authority as the Authority for Advance Rulings constituted under subsection (1) or authorised under subsection (2A) of section 28F of the Customs Act, thereby tying the Central Excise definition to the Advance Rulings mechanism established under the Customs Act.