<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by drbala:
Is the following routing permissible
ARN-LHR-ORD-LAX-HKG-JNB-LHR-MRU-LHR-ARN
IMHO seems to fit the above rule.</font>
Only if there is also an exception for Africa that wasn't mentioned. You have two intercontinental departures from there, JNB-LHR and MRU-LHR.