Originally Posted by
lowjhg
S fare is über expensive, almost matching J fares.
Not true - there is a massive difference between S & any J fares (roughly 2.5 - 3X). At least for the market i'm familiar with (UK).
SQ has a logic in their sub-classes which other airlines would do well to follow. S is the highest Economy fare (above Y) but combinable with pretty much everything from V to P.