Jon - exactly right. Unless a oneworld carrier flies to somewhere else in Egypt you have no choice but to finish the journey in CAI (where you started). I think the simple version of the rule is if you start your journey in a country that is served by one or more oneworld carriers to several cities in that country then your choice of starting and ending cities can be different. But you may not start your journey in one country then finish in another, even if they are in the same region.
[This message has been edited by mgm (edited Dec 22, 2003).]