Mixed 121 & 117 rules.
Tracking of 121 & 117 regulations for those of us flying both passengers and cargo in any given month. Ability to run legality scenarios with both sets of regulations, and automatic selection based on operation type.
I don't know who flies BOTH sets of regs but I fly cargo only and 117 doesn't apply. I'd love the functionality of APDL but it simply does not apply to me. There are thousands of pilots between UPS, FedEx, Atlas, ABX, National, Kolitta, etc that could benefit from this.