Subsection (1) provides that sections 19 to 43, Parts II to V (sections 44 to 111) and sections 117 to 124 and section 125 (in relation to certain provisions in Schedule 8) are to come into force on such day as the Secretary of State may by order appoint.  This order is not subject to any Parliamentary procedure.  Section 126 provides for a day appointed by such an order to be designated as the principal appointed day.  This is of relevance for the interpretation of references to enactments in Schedule 5, as provided for by Part III of that Schedule.
Subsection (2) provides that different days may be appointed for different purposes.
This power has been exercised by the Secretary of State in making the Scotland Act 1998 (Commencement) Order 1998 (S.I. 1998/3178).
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