If I recall correctly, it was pretty standard stuff: Business/*A Gold -> Asiana Gold -> Everyone else (I don't remember if they used two groups for Economy or if I got it mixed up with another airline, but if they did it was basically back half then front half). They don't use zones or boarding groups, but as with most Asian carriers, I found boarding pretty painless with cabin storage easy to find. Off-topic, but it blew my mind that a 2 hour flight in the USA in a Q300 would still use seven odd boarding groups and the gate agent would just rattle them off one by one before boarding.