The Parliamentary Voting System and Constituencies Act has three parts and twelve schedules. Part 1 of the Act provides for a referendum, to be held on 5 May 2011, on whether to change the voting system for the United Kingdom parliamentary elections. It prescribes the question to be asked, and includes provisions which make the amendments to the existing electoral legislation that it would be necessary to make to implement the alternative vote system in the event of a 'yes' vote in the referendum. Part 2 of the Act provides that the number of parliamentary constituencies in the UK will be reduced to 600. Part 3 sets out the repeals, financial provisions and territorial extent of the Act. The rules for drawing up the revised constituencies will ensure the Boundary Commissions give priority to numerical equality as a principle. There will be a uniform electoral quota for the UK, and seats may not vary by more than 5 per cent from the quota, with some limited exceptions. Regular redistributions would take place every five years. The Parliamentary Boundary Commissions are to conduct a review by the end of September 2013 with subsequent reviews every five years.