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...

Curious, can you elaborate on what “completely auditable” means?

In short: the system should log every operation performed within, and that log should be readily accessible to (authorized) end-users.

For example: let's say you have a warehouse management system, which tracks inventory movements in a warehouse / fulfillment center that ships, say, toothbrushes to customers. Multiple customers call in with complaints about getting blue toothbrushes when they ordered red toothbrushes. Seeing as how this is clearly not an isolated incident (multiple people are upset about not getting the right toothbrush!), it's up to you to find out where in the whole lifecycle of that toothbrush in your warehouse - all the way from when it was received to when it was shipped - that error might be happening. If your warehouse management system is completely auditable, then you'll be able query the transaction log (given perhaps the affected order and item numbers) to work backwards to investigate where the fault occurred, be it in shipping, picking, replenishment, receiving, the vendor, or what have you.

The "incumbent" off-the-shelf ERP and WMS vendors tend to support this sort of comprehensive audit trail much more thoroughly than those writing new ones (whether as an in-house project or as a startup attempting to disrupt the space), simply because those incumbents have already had their hard-earned lessons on why literally every transaction must be thoroughly logged (whereas the newcomers and DIYers typically have not, or are in the process of learning as they encounter more and more situations where that audit trail is necessary).

That. Also the financial aspect of any transaction is important. Just this week I had a chat concerning point-of-sales systems with an accountant in Germany. Tax authorities require that any record has to be impossible to alter afterwards. Same goes for ERP systems, every transaction has to be able to be backtracked, every change has to the books has to be recorded.

Any system, e.g. SAP, that has a proofen track record in that, that is SOX compliant, is a huge benefit in that regard. Also for the company itself, IMHO, as the company is forced to work in compliant ways that just make life a lot easier.

where I am, it means “so-and-so took such-and-such an action with these permissions at this time” which can be correlated with things like “this was the exact configuration of the entire system at the time” with reliability and immutability, across multiple versions.