How do I know a number in my ERP is right?
In most systems you do not, and the honest answer is that you trust it because it has been broadly right before. The alternative is to make every figure descend: a balance opens into the journals that make it, a journal into the document that caused it, a document into what a machine or a person decided and what they decided it from. Where nothing sits beneath a record, the surface says so rather than dead-ending, because a link that goes nowhere and a record that has nothing below it are indistinguishable otherwise, and the second one quietly erodes trust in every other figure on the screen.
Why drilling down usually stops working
Most systems have drill-down on the surfaces somebody remembered to build it on. Built per screen, it is inconsistent within a quarter, and the inconsistency is invisible: each screen looks fine on its own and only somebody who uses two of them notices that one dead-ends.
So it has to be one mechanism used by every surface, and entering the trail partway down has to land in the same place, looking the same, as walking down to it.
What each step has to carry
Not just where it goes but what the relationship means. Posted from and evidenced by are different claims about the same pair of records, and a reader checking a figure needs to know which one they are following.
And the edges have to include the ones that are refusals. When the next step exists and is closed to you, saying so is more use than hiding the edge, because an absent edge reads as an absent record.
The number nobody thinks to ask about
As at when. A trial balance with no time on it fails on the first question an auditor actually asks, which is not where did this come from but as at what moment was this true.
Every figure here carries the moment it was read, taken from the database rather than the browser, and past a few minutes it says so rather than continuing to present stale figures as current.
What this does not do
A trail terminates where a document store would be, because there is not one: the system holds a named person's attestation that they have the supplier's invoice, not the invoice. That is described that way rather than dressed up. Bitemporality, being able to ask what the books said on a date given what was known then, is not built.