Curiouser and curiouser. I called to amend my booking today, and was told that I must depart within 12 hours of arriving..... otherwise it becomes a stopover and not a connection.

So - there's a brand new number. 12 hours constitutes a stopover.

(Incidentally, the res agent I spoke with was excellent - polite, well informed, and checked again specifically for me. I have confidence that she gave me a policy rule, and not a "get this guy off the phone" line).