Explanation under Section 11(3) confirmed effective from inception of concessional entry, clarifying retrospective operation period. The explanation excluding Government and Local Authority activities from the term 'business' in Sl. No. 3(vi) of notification No. 11/2017 CTR, inserted by notification No. 17/2018 CTR, was made under Section 11(3) and therefore operates from the inception of the original concessional entry; a subsequent line in the later notification stating a later commencement date does not alter that retrospective operation.