Originally Posted by themicah

Given that YXU (London, ON) is only 126 miles from DTW, it wouldn't make much sense to route via NRT AMS or CDG.

To the OP: a "segment" is generally a flight number. That means you'll get a segment credit for each flight you take, as long as you don't take any "direct" flights where two flights have the same flight number. For example, if you fly NW758/NW250 MSP-DTW-FLL, you'll get two segment credits, whereas if you take NW250 "direct" MSP-DTW-FLL, you'd only get one.