<font face="Verdana, Arial, Helvetica, sans-serif" size="2">What if you schedule a more than 24 hr stopover! Then even if Q,V,W is available, won't it automatically price as H or M?
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Nope. The system may just $100 for a stopover that cannot be included in the fare class (e.g. SFO-NRT-SIN-NRT-HNL[stop]-SFO. might be a Q + $100).