The way to fix a wrong sale is void-and-replace: void the bad transaction, then enter a fresh, correct one. This field on the new transaction points back at the old one, so the pair reads as "this corrects that."
Following the chain shows the full story — original sale, the void, and the correction — without ever destroying a record. Reports count only the live correction, not the voided original.
Technical section
Data model, API, and internals — visible to developers.