The fare codes change as to their meaning but, apart from reward ticket codes (D for business and W for economy class), they generally start at L as the lowest discount fare available (not necessarily available on all flights at all times, reserved for seat sales etc.). The next fare up the rung is Q class which is their standard 14 day advance booking (not always 14 days but usually) with a usual Saturday overnight stay. V class is next, often a 7 day advance booking and a usual Saturday overnight. Their premium fares (still discounted) are at H and B or M. The B or M fares require advance purchase but are usually fully refundable. whereas the other lower classes are not. Y= full economy, changeable and fully refundable (although even here there are some discounted types, e.g. YHE9 is a Y fare but it requires a 7 day stay but cost about half the normal Y fare). J or C= Executive or Executive First. Air Canada allows qualifying or Q miles on all its "published" fare classes (those above). I am not sure if Z is a consolidator fare (and therefore not published) which may not be eligible for Q miles--check with Air Canada. Elite upgrades in North America are good on any fare, even L.