Okay. So correct me if I've misunderstood but we have a situation where, in order to make the most of the 20 segment rule, the xONEx:

1) can be booked no later than 31 May 2008 (or 27 May 2008 if taking advantage of the last day of the low season fares)
2) can have a date for the first international segment no later than 21 May 2009 (bookings available 355 days in advance) (or 17 May 2009 if taking advantage of the low season fares)
3) must be completed within 12 months of the date of the first flight, be that transcontinental or international
4) can be changed (re-routing, changed ports etc.) after the pre-1 June 2008 initial booking date (31 or 27 may 2008, in this example), without penalty, provided the journey hasn't commenced.

Have I missed anything?

(This assumes the origin is SWP.)