Originally Posted by JJeffrey

This comes up fairly often as aa.com does a not so good job of displaying fare rules and this type of thing. An ORD-ICN fare in Prem Econ that books into O/P will almost certainly have change fees associated with it. P is discount premium economy, while W is full fare premium economy.

But the only way to know for certain is to check the specific fare rules. You can do a dummy booking at aa.com, click through like you're going to buy the ticket, on the very last page before you click "purchase" there will be a "Detailed Fare Rules" link at the bottom. Click that, then scroll down to the penalties sections to see what fees there would be for cancellation and/or changes.