Build and verify
Reachability is a number, not an adjective.
The first thing agreed is what the file is for. Columns are standardised to one definition each, and the original kept beside it. Nothing is enriched from a source that cannot be named.
Suppression
Exclusion lists applied properly, so a record you asked to withhold stays withheld.
Encoding repair
Fixing characters mangled in transit before they reach a system that will mangle them again.
Industry mapping
Translating described activity into the classification your systems already use, including where it fits badly.