There has been a change in the 2014 ORR Rule Book that now requires a minimum ISP measurement. The minimum ISP measurement will be used for the purposes of calculating the minimum rated spinnaker area.
Most boats will see no change in their rating certificate, any certificate issued in the future will reflect this rule change and any boat that is currently affected by this change will receive a new valid certificate. There is nothing you need to do, it will all happen automatically.
A copy of the latest Rule Book can be found here.