The Kiwaussie Flag is a geographic flag. It is to be flown anywhere in Australia or New Zealand where they are at equal latitude. Thus the second biggest island of Australia and second biggest island of New Zealand can fly this flag anywhere, since they are at parallel latitudes. Coincidentally the second biggest island of Australia is a south island, while the second biggest of New Zealand is the north Island.
Both capital cities can fly this flag since both are parallel to each other. It's a flag to be flown from Adelaide to Auckland, with Melbourne in the middle.