I am not totally clear about your question with those As, Bs... (well, it's 6am here now so I'll take a look at it later.)
Anyways, here's what I think right now.
<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by newbe:
Remains the question regarding the mentioned side trip ...L-M-L-...
Any idea? All I know is that you can go through intermediate points more than once as long as that isn't the origin or the destination of the trip. (But if you are able to travel through intermediate points more than once, every loop could be condidered a side trip triggering the HIP rule - or am I wrong?)</font>
Remember that international travels are governed by MPM so you probably can't go do too many 'side trips' so that's probably a non-issue. As for whether the L-M-L would trigger the HIP, answer should be yes.
If you can give some city pairs, maybe I could understand your question better. Sorry couldn't be more helpful at this point. Need some coffee.