If you're flying Supplemental international under 121.513 you'er screwed. If they keep your "aloft" time under 20 in 48 or 24 in 72 all you get is one in seven. You can literally be on "duty" six days straight.

And don't hold your breath waiting to hear from the FAA. You can pull interpetations from the Chief Counsel on the FAA web site. Some of them are dated a year after the letter asking for clarification.

Guys we (Air Carrier Compliance Group) write to the FAA for interpetations all the time for questions just like this. its the only way I know of to get a "legal" interpetation. If you want the address let me know.