Four actions on one endpoint. create opens a slot with its position, length, reserve price and closing time, and returns an admin token that only the opener holds. bid places a sealed bid, checked against the reserve, the slot length and the publisher's excluded categories before it is accepted — a rejected bid is recorded with its reason rather than silently dropped, so a bidder can see why it never competed.
https://audio.halowerk.com/ad-slot-auction