Definition of applicant expanded to include customs, central excise and finance applicants, widening advance ruling eligibility. The amendment broadens the definition of applicant in section 245N to include specified non-residents and residents, classes of persons notified by the Central Government, applicants making applications under section 245Q, and applicants as defined under corresponding provisions of the Customs Act, the Central Excise Act and the Finance Act, thereby widening eligibility for advance rulings under Chapter XIXB.