Every channel data problem eventually reduces to this. Your partner’s part number is not your part number; their end-customer code is not your customer ID; their ship-to hierarchy has a different shape from yours. Matching by exact string join fails, and it fails **silently**.
That silence is the whole issue. An unmatched transaction does not error — it lands in a suspense file with no owner, does not accrue, does not count toward a tier, and never appears in a report as missing. Match rates of 82–92% are typical, which means up to one line in six is invisible.
A cross-reference layer holds the mappings, resolves many-to-one relationships, and — critically — surfaces what it cannot resolve as a worked exception queue rather than dropping it.