Sell-in is what you shipped to the distributor. Sell-through is what the distributor sold onward. They diverge whenever channel inventory moves, and only sell-through reflects real demand.
Sell-through is also the evaluation basis for most channel programmes: end-customer volume tiers, design-win claims, grower and operator rebates, and chargeback validation all depend on it. Which makes the match rate — the share of reported lines that resolve to your products and customers — one of the most consequential numbers in a channel business.
Typical match rates sit between 82% and 92%. The unmatched remainder does not error; it lands in a suspense file, does not accrue, does not count toward a tier, and never appears in a report as missing. A cross-reference layer is what moves this above 99.5%.