In the ALPA calendar red pages there is a detailed description of your options. It is well written but can still be a bit confusing. Overage is almost always a good deal unless the company builds you an immediate dh to base the next day. BTW.....when the company initially rebuilds the pairing immediately after you get sent back to the hotel, there will be an updated credit hour value of the trip. This can still change and actually be a lower value if another rebuild occurs and they dh you home. This is what can lead to overage not being the best deal but you will at least be made whole with the additional 3+30 you will get from the extra duty period pay you will be due (need to put in for that additional pay also). Good luck.