Auditable includes financial auditing. It should be possible and simple to reconstruct the state of a customer account at any point in time. What products they had, what discounts and promotions were in place, how they were purchased and what was owed at that exact point in time.

It is scary how many systems cannot be audited this way because the engineers and business owners had no understanding of basic accounting concepts like double entry book keeping.

Systems that are not designed to be easy to financially audit are either going to overbill or underbill customers. It isn’t a matter of if, but when...