Extra place
An extra-place offer is a bookmaker paying each-way place terms on more finishing positions than usual, such as four places where three is standard.
The exchange's place market still settles on the usual number of places, and that gap is the whole appeal for matched bettors. A runner that finishes in the added place wins the place part of the bookmaker bet, while on the exchange it counts as unplaced, so the place lay wins as well.
Each part is laid like a qualifying bet, lay stake = part stake × part odds ÷ (lay odds − commission), where the place part's odds are 1 + (win odds − 1) × the place fraction. Take 5 units each way at 9.0 with one-fifth terms and four places, against an exchange place market paying three, so the place part is a bet at 2.6.
At 2% commission (use your own rate), the win is laid at 10.0 for 4.51 units and the place at 2.7 for 4.85 units. Whether the horse wins, finishes second or third, or is unplaced, the position loses 0.83 units. If it finishes fourth, in the extra place, the bookmaker pays the place part, 8 units, and both lays win because the exchange's place market paid only three. The position ends 12.17 units up.
In the OddsRelay feed
On GET /v2/odds/extra-place, each back[] offer carries places, the number of places that bookmaker pays, and place_fraction, its place terms as a decimal, 0.2 for one-fifth. lay is an object of two arrays, win and place, each lowest price first, and every lay.place offer carries places too, the number the exchange's place market settles on. Comparing back[].places with lay.place[].places shows the extra places directly.
Because places sits on each back offer, one outcome can list bookmakers paying different numbers of places side by side, and the one with the most places is not always the one with the best price. Offer terms, including which races qualify and any maximum stake, are set by each bookmaker and can be withdrawn from an individual account. The feed carries the prices and the place terms. Eligibility stays with the bookmaker.
Try it on your own key
Every plan includes every feed. Sign up free and call any of them.