Just called the AA RTW desk to check availability for a DONE4 itinerary that I was pretty sure was valid:

OSL-HEL-LHR-YVR-NRT/HND-SYD-SIN-HND-TSA/HND-BKK-HND-LHR-TOS/OSL
(stopovers in bold, surface segments marked with /)

To my surprise, I was told that after having stopped in NRT and SYD earlier, I cannot stop in SIN or anywhere else in Asia -- I can visit Asia again but only for transits.

I asked the agent which rule this was violating and she couldn't give me an answer other than "computer says no"... I pointed her to 4(e) which states that two intercontinental departures and two intercontinental arrivals are permitted for Asia, but she wouldn't budge.

Am I missing something? I've re-read the rules twice and cannot find anything wrong with my routing.