Requirements are read back as filters before anything is run. A sample is pulled and read before the full run is committed. Each delivery says how old its parts are.
Spelling normalisation
Settling variant forms of the same organisation name so counting does not double.
Known-gap register
A written list of what the file does not contain, kept with the file.
Field population report
A per-column statement of how much is filled, delivered with the file rather than on request.
Say what success looks like and we will tell you if the data reaches it.