Every buyer gets a number (buyerNumber) — the integer the auctioneer and ring clerk shout and record when a lot is knocked down. It must be unique within your barn, so two buyers can never share the same number.
A buyer number is unique per tenant and is what ties a winning bid to a buyer. Reusing a number for a different person will misattribute purchases and invoices.
Technical section
Data model, API, and internals — visible to developers.