Back to back means you can join one month's days off onto the next. So, for instance, you could have last 14 days of June (10 days off + 2 commuting days + 2 vacation days) and add them to the first 14 days of July (or even more if you have other vacation days to use.....of your 24 per year). You will, of course, then have to make up that time by spending longer in Japan and could find yourself 5-6 weeks away from home. Some people do this a lot in order to reduce the jet lag by having two commutes and, also, saving one commute and getting $2000.
As has been said all along, probably the best bit of this whole contract is the flexibility of the days off and long may it continue because it is the only thing that is keeping some people here. AJX management realise this but there are a lot of envious people in ANA and they don't like the 'freedom' we seem to have, so there is continuous pressure for AJX to gain more control of the days off and they would like nothing better to have set blocks and/or allocate time off. If this ever happened then I would certainly be on the next flight out of Japan with many others but that doesn't mean they won't keep nibbling away.
And kind of on that subject, yes it is true that AJX requires an absolute minimum of 9 hours for you to rest before a duty, having commuted into work. BUT they are being very generous in allowing that and it is absolutely imperative that people don't abuse it or muck it up for everyone else by not managing their inbound flights or getting sufficient rest before a duty. The contract call for you to commute into Japan on the last day off and they could enforce that if anybody screwed up. The original 'alleviation' was put there so that Oz commuters could arrive early (before 0600) on the first day of duty because to arrive the day before would mean leaving the day before that i.e. a day off instead of a commuting day. It is not meant to be there as a free-for-all to push the limit. I say all this because you should not plan to come to AJX based on getting in to Japan with minimum time to spare. As with all 'privileges' be it staff travel, days off, extra payments etc there will always be some ******** who spoils it for everyone else. You should plan on that ******** doing exactly that and the 9 hour 'alleviation' not being an option in order to best compare your time off. In other words, plan for the worst and hope for the best.