Address standardisation
Specifications first, records second.
If a requirement can be specified it can be sized, and sizing happens first. The file is deduplicated against anything previously supplied to you. The file is built to be used, not to be impressive.
Classification check
Verifying categories against the underlying description rather than trusting a label applied upstream.
Repeatability
The same brief run twice produces the same file, because the definition is recorded.
Header verification
Confirming the column order matches the specification before the file is sent.