Paragraph 3 applies where the Boundary Commission for Scotland submits a report to the Secretary of State under section 3(1) or (3) of the Parliamentary Constituencies Act 1986 making recommendations for the alteration of UK Parliamentary constituencies (sub‑paragraph (1)).  It effectively provides that, in such a case, the Commission must also consider whether or not changes are also required to be made to the boundaries of regions and the number of seats for those regions in order to give effect to the rules in paragraph 7 (sub-paragraph (2)).
Sub-paragraph (4) requires any report by the Boundary Commission recommending alterations to any region to state the name by which the region should be known and the number of regional members to be returned for it.  Sub-paragraph (5) requires the Boundary Commission to lay before the Parliament any report recommending changes in parliamentary constituencies. This is in addition to the existing requirement of the Boundary Commission to lay its reports before the UK Parliament.
Paragraph 4(1) provides that an Order in Council under section 4 of the 1986 Act which alters any constituency or region may come into force for the purposes of elections to the Scottish Parliament on a different date from that on which it comes into force for the purposes of elections to the UK Parliament.
Paragraph 4(2) provides that the coming into force of such an Order in Council will have no effect on the return of any member, or on the constitution, of the Parliament until the Parliament is dissolved.
Reports of the Boundary Commission