Originally Posted by WineCountryUA

there is not one set of fare rules for each fare class. The fare rule is based on the complete fare designation (BUA vs BA0GY for SFO-EWR or BUA vs BA0KY for IAH-EWR). Some fare classes for a particular OD can have half dozen separate fare rules.

If you did not capture your specific fare rules at booking, you can try a dummy booking and see if the same one is still available. Alternatively you can look up the presently available fares at www.farecompare.com and your fare rule may still be posted.