Commencement of IGST provisions: specified sections activated to establish registration, definitions and rulemaking framework. Notification issued under section 1(3) of the IGST Act appoints an appointed day to bring into force specified sections of the Act, thereby activating provisions on commencement, definitions, officers, registration, application of certain CGST provisions to IGST, and the power to make rules to establish the IGST administrative and procedural framework.