I researched this a little having had AONE3's issued in Australia. As it's not possible to issue an AONE3 starting in Australia (the minimum being an AONE4), no AONE3 fare exists; therefore the fare of the country of origin is used. Once we go to an ANOE4 which does exist in Australia, the country of origin fare (e.g. Qatar) is compared to the country of issue fare (Australia), and the latter has to be charged as it's higher.

Reissuing after the first leg is possible, but not at the country of origin price.