Provenance
Every field names its source, its block, and the code that produced it.
Why every field
No competitor tells you where a number came from. When our figure disagrees with another vendor's, provenance is what makes the disagreement diagnosable rather than a matter of opinion.
Correctness
Correctness note
A DERIVED source means we computed the value rather than observed it. If a number matters to your books, check whether it is observed or derived — and if derived, the invariant suite tells you how it is checked.